JP2018055029A - Quantum dot sheet, backlight and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quantum dot sheet with an improved hue of an edge area.SOLUTION: A quantum dot sheet includes: a laminate (A) having a light permeable substrate (i) on one side of a quantum dot containing layer that contains a quantum dot configured to absorb primary light and emit secondary light and a binder resin, and a light permeable substrate (ii) on the other side thereof; and an encapsulation part (B) formed on at least part of an edge face on a thickness direction side of the laminate (A). The encapsulation part (B) has a curved surface shape projecting opposite to the laminate (A) side with reference to the edge face.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a quantum dot sheet, a backlight, and a liquid crystal display device.

  Developments for improving the light emission efficiency and color rendering of liquid crystal display backlights and lighting devices are advancing. In recent years, in order to realize such a light emitting device, a combination of a light source that generates primary light (such as a blue LED that emits blue light) and a quantum dot phosphor made of semiconductor fine particles (hereinafter referred to as “quantum dots”). Light emitting devices are being developed.

The quantum dot is, for example, a nano-sized compound semiconductor particle composed of a semiconductor particle composed of a core made of CdSe and a shell made of CdS and a ligand covering the periphery of the shell. The quantum dot has a quantum confinement effect because its particle size is smaller than the Bohr radius of the exciton of the compound semiconductor. Therefore, the luminous efficiency of the quantum dots is higher than that of a phosphor (rare earth phosphor) that uses a rare earth ion as a conventional activator, and a high luminous efficiency of 90% or more can be realized.
In addition, since the emission wavelength of the quantum dots is determined by the band gap energy of the compound semiconductor fine particles quantized in this way, an arbitrary emission wavelength, that is, an arbitrary emission spectrum can be obtained by changing the particle diameter of the quantum dots. Can do. By combining these quantum dots with a blue LED or the like, it is possible to realize a backlight with high luminous efficiency and high color rendering (see, for example, Patent Documents 1 to 3).

As a method of incorporating quantum dots into a backlight device, an on-chip method of incorporating quantum dots in a light source, an on-edge method of arranging a transparent tube containing quantum dots between a light source and a light guide plate, and a light output side of the light guide plate In addition, an on-surface method is known in which a sheet containing quantum dots (quantum dot sheet) is disposed on a light source.
However, in the on-chip method, since the quantum dots are incorporated in the light source, the quantum dots are exposed to a high temperature, and the conversion efficiency of the quantum dots is inferior. In the on-edge method, since the transparent tube containing the quantum dots is disposed between the light source and the light guide plate, the size of the backlight device is increased. In particular, in mobile devices, it is difficult to cope with the on-edge method because downsizing of the backlight device is required.
On the other hand, the on-surface method does not have the above-mentioned problem, and it is also possible to use a conventionally used backlight device. For these reasons, it is currently being studied to incorporate quantum dots into a backlight device by an on-surface method.

International Publication No. 2012/132239 Japanese Patent Laying-Open No. 2015-18131 Japanese Patent Laying-Open No. 2015-28139

  However, an on-surface type backlight using a quantum dot sheet sometimes has a tint instead of a white edge region.

  An object of this invention is to provide the quantum dot sheet, backlight, and liquid crystal display device which improved the color of the edge area | region in view of the said problem.

In order to solve the above problems, the present invention provides the following quantum dot sheets, backlights, and liquid crystal display devices of [1] to [3].
[1] A light-transmitting substrate (i) on one surface of a quantum dot-containing layer containing a quantum dot and a binder resin that absorbs primary light and emits secondary light, and a light-transmitting substrate ( ii) and a sealing part (B) formed on at least a part of the end face on the thickness direction side of the laminated body (A), and the sealing part (B) ) Is a quantum dot sheet having a curved surface shape that is convex on the side opposite to the laminate (A) side with respect to the end face.
[2] At least one light source that emits primary light, an optical plate that is disposed adjacent to the light source and that guides or diffuses light, and a quantum dot sheet that is disposed on the light exit side of the optical plate. The backlight provided, wherein the quantum dot sheet is the quantum dot sheet according to the above [1].
[3] A liquid crystal display device including a backlight and a liquid crystal panel, wherein the backlight is the backlight according to [2].

  The quantum dot sheet, backlight and liquid crystal display device of the present invention can improve the color of the edge region.

It is a fragmentary sectional view showing one embodiment of the quantum dot sheet of the present invention. It is a perspective view which shows one Embodiment of the laminated body (A) which comprises the quantum dot sheet of this invention. It is a fragmentary sectional view showing other embodiments of the quantum dot sheet of the present invention. It is a fragmentary sectional view showing other embodiments of the quantum dot sheet of the present invention. It is a fragmentary sectional view showing other embodiments of the quantum dot sheet of the present invention. It is a fragmentary sectional view showing other embodiments of the quantum dot sheet of the present invention. It is a fragmentary sectional view showing other embodiments of the quantum dot sheet of the present invention. It is sectional drawing which shows one Embodiment of a laminated body (A). It is sectional drawing which shows other embodiment of a laminated body (A). It is sectional drawing which shows one Embodiment of the backlight of this invention. It is sectional drawing which shows other embodiment of the backlight of this invention. It is sectional drawing which shows one Embodiment of the liquid crystal display device of this invention. 6 is a partial cross-sectional view showing a quantum dot sheet of Comparative Example 4. FIG.

Embodiments of the present invention will be described below.
[Quantum dot sheet]
The quantum dot sheet of the present invention comprises a quantum dot containing a quantum dot that absorbs primary light and emits secondary light and a quantum dot-containing layer containing a binder resin on one surface and light on the other surface. Comprising a laminate (A) having a permeable substrate (ii), and a sealing portion (B) formed on at least a part of an end face on the thickness direction side of the laminate (A), The sealing part (B) has a curved surface shape that is convex on the side opposite to the quantum dot-containing layer with respect to the end face.

  FIG. 1 is a partial cross-sectional view showing an embodiment of a quantum dot sheet 100 of the present invention. The quantum dot sheet 100 of FIG. 1 is a laminate (A) 60 having a light transmissive substrate (i) 21 on one surface of the quantum dot-containing layer 10 and a light transmissive substrate (ii) 22 on the other surface. The sealing portion (B) 90 is formed on at least a part of the end face 63 on the thickness direction side of the.

<Sealing part (B)>
The sealing portion (B) is formed on at least a part of the end face on the thickness direction side of the laminate (A), and has a curved shape that is convex on the opposite side of the laminate (A) with respect to the end face. doing.
In this invention, the color of the edge area | region of a quantum dot sheet can be improved by having a sealing part (B). Hereinafter, the reason why this effect is produced by having the sealing portion (B) will be described.

First, the cause of the problem of the color of the edge region will be described.
Secondary light emitted from the quantum dots diffuses evenly at 360 degrees. On the other hand, the primary light has directivity and the diffusion direction is not uniform. In addition, among the primary light, the light that is transmitted without being absorbed by the quantum dots has directivity and the diffusion direction is not uniform.
Accordingly, when the primary light is incident on the quantum dot sheet, the secondary light is uniformly diffused among the transmitted light, while the primary light has directivity. The secondary light that is uniformly diffused diffuses a large proportion of light up to a high angle, and light tends to leak from the end surface on the thickness direction side of the quantum dot sheet, while the primary light has a proportion of diffused light at a high angle. Little light leaks from the end face. For this reason, the end face (edge region) of the quantum dot sheet has a large proportion of primary light and is colored with primary light (when the primary light is blue, it becomes bluish).

Here, when the sealing portion (B) is provided on the end surface on the thickness direction side of the laminate (A), a part of the primary light leaking from the end surface is entirely formed by the convex curved surface of the sealing portion (B). Reflects and returns to the laminate (A) side. The returned primary light is absorbed by the quantum dots, and secondary light is emitted from the quantum dots. Furthermore, part of the secondary light leaking from the end face is also totally reflected by the convex curved surface of the sealing portion (B) and returns to the laminate (A) side.
That is, when the sealing part (B) is provided on the end face on the thickness direction side of the laminate (A), the primary end face (edge region) of the quantum dot sheet is compared with the case where the sealing part (B) is not provided. The proportion of light can be reduced and the proportion of secondary light can be increased. For this reason, it can suppress that an edge area | region takes on the color of primary light by having a sealing part (B).
In addition, even if it is a case where a sealing part is formed in the end surface by the side of the thickness direction of a laminated body (A), this curved surface becomes convex on the opposite side to a laminated body (A) side on the basis of an end surface In the case of not having a shape, the effect of the total reflection described above is hardly received, so that the color tone problem in the edge region cannot be solved.

  Moreover, since the sealing part (B) is a curved surface shape, when a load is applied to the sealing part (B), it is easy to disperse the load, and it is possible to easily suppress a large load from being applied locally. Therefore, by making the sealing part (B) into a curved surface shape, it is possible to easily prevent the sealing part (B) from being damaged or peeled off when the quantum dot sheet is cut or the quantum dot sheet is transported.

The “end surface 63 on the thickness direction side of the laminate (A) 60”, which is a location where the sealing portion (B) is formed, refers to a surface that is substantially parallel to the thickness direction of the laminate (A) 60. . If the laminate (A) is a general quadrangular prism structure, the laminate (A) has four end faces 63. In FIG. 1, the surface along the arrow in the drawing is the end surface 63, and the shaded surface corresponds to the end surface 63 in FIG. 2.
Hereinafter, the “end surface on the thickness direction side of the laminate (A)” may be referred to as “end surface of the laminate (A)”.

The sealing part (B) should just be formed in at least one part of the end surface of a laminated body (A).
As a structure which has a sealing part (B) in at least one part of the end surface of a laminated body (A), for example, (i) As shown to Fig.3 (a), a sealing part (B) is a laminated body (A). (Ii) forming a sealing portion (B) on an arbitrary end surface of the end surfaces of the laminate (A), as shown in FIG. 3 (b), A configuration in which the sealing portion (B) is not formed on the other end surface, and (iii) a configuration in which the above configurations (i) and (ii) are combined.
There are various configurations of the backlight, and the emission angle distribution of the primary light emitted from the backlight is different depending on the configuration of the backlight, and the directivity tendency of the primary light is different. For this reason, the color of the end surface (edge region) of the quantum dot sheet tends to be different depending on the configuration of the backlight. More specifically, the quantum dot sheet has a plurality of end faces (edge regions), but depending on the configuration of the backlight, an end face in which a color problem appears remarkably, and an end face in which a color problem is unlikely to occur. Will be mixed. For this reason, it is preferable to form a sealing part (B) in the end surface where the problem of a color tone appears notably. In the case of an edge light type backlight, there is a tendency that a color problem tends to occur on the end surface (edge region) on the light source side, so a sealing portion (B) is formed on the end surface located on the light source side of the edge light type backlight. It is preferable to do.
In addition, the sealing part (B) 90 is on the thickness direction side of the laminated body (A) 60 and the laminated body (A) 60 side with respect to the end surface of the laminated body (A) 60, as shown in FIG. It may be formed protruding.

  The sealing part (B) is preferably formed in substantially the entire region of the end surface of the laminate (A) from the viewpoint of further suppressing the color of the edge region and suppressing the deterioration of the quantum dots. The substantially total region refers to 90% or more of the total area of the end face of the laminate (A), preferably 95% or more, more preferably 99% or more, and still more preferably 100%.

  The sealing portion (B) curved surface shape may be a macro curved surface shape as long as the effects of the present invention are not impaired. For example, when the surface of the sealing portion (B) has a fine uneven shape, it has a non-curved surface shape microscopically, but can be said to be a curved surface (pseudo curved surface) macroscopically.

In the sealing part (B), the cross-sectional shape of the sealing part (B) when the quantum dot sheet is cut in a direction parallel to the thickness direction and perpendicular to the end face on the thickness direction side of the laminate (A) is as follows. It is preferable to satisfy (1).
<Condition (1)>
Among the lines constituting the outer frame of the cross-sectional shape of the sealing portion (B), the line overlapping the line formed by the end face on the thickness direction side of the laminate (A) is the line L, and the laminate (A The arc-shaped line that is located on the opposite side of the) side and forms the curved surface shape is defined as a curved line M. When a perpendicular is drawn with respect to the line L from an arbitrary point O on the curve M, the maximum value of the length of the perpendicular is defined as the height h of the cross-sectional shape. Furthermore, when the length of the line L is d, the relationship of 0.20 ≦ h / d ≦ 0.80 is satisfied.

As described above, the sealing portion (B) has a curved surface shape that is convex on the side opposite to the laminate (A) side with the end face of the laminate (A) as a reference. When the condition (1) is satisfied, it means that the curved surface shape is close to a circular arc. For this reason, when the condition (1) is satisfied, the primary light and the secondary light leaking from the end face of the laminate (A) are easily totally reflected and returned to the laminate (A), and the edge region is the color of the primary light. It is easy to suppress the taste. Moreover, when satisfy | filling conditions (1), it becomes easy to disperse | distribute the load to a sealing part (B), and it can be easy to suppress a damage and peeling of a sealing part (B).
Condition (1) more preferably satisfies 0.30 ≦ h / d ≦ 0.70, and more preferably satisfies 0.40 ≦ h / d ≦ 0.60.

FIG. 5 is a cross-sectional view of a quantum dot sheet cut in a direction parallel to the thickness direction and perpendicular to the end surface on the thickness direction side of the laminate (A). M, an arbitrary point O on the curve M, the height h of the cross-sectional shape, the length d of the line L, etc. are entered. In the configuration of FIG. 5, the line formed from the end surface of the laminate (A) and the line L completely overlap (the length of the line formed from the end surface of the laminate (A) and the line L The length d is equal.) Further, in the configuration of FIG. 5, the curve M is formed in an arc shape connecting both ends of the line L.
In the case of the configuration having the sealing portion (B) in a part of the end surface of the laminate (A) in the thickness direction as shown in FIG. 3, a line L is formed on a part of the line formed from the end surface of the laminate (A). It overlaps (the length d of the line L is shorter than the length of the line formed from the end surface of the laminated body (A)). In addition, as shown in FIG. 4, when the sealing portion (B) protrudes from the end surface of the laminate (A) to the thickness direction side of the laminate (A), the curve M is an extension of the line L. It is formed in an arc shape connecting both ends of the wire.
In the condition (1) and the like, “the line constituting the outer frame of the cross-sectional shape of the sealing portion (B)” is, in other words, the outer periphery of the cross-sectional shape of the sealing portion (B), and indicates the thick line in FIG. .

In the sealing part (B), the cross-sectional shape of the sealing part (B) when the quantum dot sheet is cut in a direction parallel to the thickness direction and perpendicular to the end face on the thickness direction side of the laminate (A) is as follows. It is preferable to satisfy (2).
<Condition (2)>
Among the lines constituting the outer frame of the cross-sectional shape of the sealing portion (B), the line overlapping the line formed by the end face on the thickness direction side of the laminate (A) is the line L, and the laminate (A The arc-shaped line that is located on the opposite side of the) side and forms the curved surface shape is defined as a curved line M. Let N be the midpoint of the line L. An arbitrary point on the curve M is defined as O, and a straight line connecting the middle point N and the arbitrary point O is defined as a straight line P. Let Q be the slope of the straight line P with respect to the line L. An arbitrary point O is moved along the curve M so that the inclination Q changes by 5 degrees from 5 degrees to 175 degrees, and the length r of the straight line P at each inclination is calculated. When the average length of 35 lengths r is r _ave , the minimum value of length r is r _min , and the maximum value of length r is r _max , r _min / r _ave is 0.40 or more. R _max / r _ave satisfies the relationship of 1.60 or less.

As described above, the sealing portion (B) has a curved surface shape that is convex on the side opposite to the laminate (A) side with the end face of the laminate (A) as a reference. When the condition (2) is satisfied, it means that the curved surface shape is substantially equal to the arc of the circle. For this reason, when the condition (2) is satisfied, the primary light and the secondary light leaking from the end face of the laminate (A) are easily totally reflected and returned to the laminate (A), and the edge region is the color of the primary light. It is easy to suppress the taste. Moreover, when satisfy | filling conditions (2), it becomes easy to disperse | distribute the load to a sealing part (B), and it can be easy to suppress a damage and peeling of a sealing part (B).
In the condition (2), r _min / r _ave is more preferably 0.60 or more, and further preferably 0.80 or more. In the condition (2), r _max / r _ave is more preferably 1.40 or less, and further preferably 1.20 or less.

  FIG. 6A is a cross-sectional view of the quantum dot sheet cut in a direction parallel to the thickness direction and perpendicular to the end surface on the thickness direction side of the laminate (A), and a line L necessary for calculation of the condition (2). FIG. 6B is a diagram in which a middle point of the line L is entered and a curve M is entered, and FIG. 6B shows the curve M necessary for calculating the condition (2) by extracting the sealing portion 90 from FIG. Information such as the arbitrary point O above, the straight line P connecting the middle point N and the arbitrary point O, and the slope Q of the straight line P with respect to the line L are entered.

In the sealing part (B), the cross-sectional shape of the sealing part (B) when the quantum dot sheet is cut in a direction parallel to the thickness direction and perpendicular to the end face on the thickness direction side of the laminate (A) is as follows. It is preferable to satisfy (3).
<Condition (3)>
Among the lines constituting the outer frame of the cross-sectional shape of the sealing portion (B), the line overlapping the line formed by the end face on the thickness direction side of the laminate (A) is the line L, and the laminate (A The arc-shaped line that is located on the opposite side of the) side and forms the curved surface shape is defined as a curved line M. Let O be any point on the curve M. Of the lines constituting the outer frame of the cross-sectional shape of the sealing part (B), the line formed by the end face on the thickness direction side of the quantum dot-containing layer is S, and the line S is on the light-transmitting substrate (i) side Let S _{1 be} the end, and S _{2 be} the end of the line S on the light transmissive substrate (ii) side. The length of the straight line connecting S ₁ and the arbitrary point O is S ₁ O, and the length of the straight line connecting S ₂ and the arbitrary point O is S ₂ O. The end of the line L on the light transmissive substrate (i) side is L ₁ , and the end of the line L on the light transmissive substrate (ii) side is L ₂ . The linear length of connecting the L ₁ and _{S 1} the length of the straight line connecting the _L 1 _S 1, _{L 2} and _{S 2} upon the _{L 2 S} 2, _{S 1} O is always _L 1 _{S 1} or more And S ₂ O always satisfies the relationship of L ₂ S ₂ or more.

The quantum dots in the quantum dot-containing layer are vulnerable to humidity and oxygen. When a light-transmitting substrate and other layers are laminated on both sides of the quantum dot-containing layer, humidity and oxygen are difficult to enter by these members. That, _{L 1} and _{S 1} and _L 2 _{S 2} is the length of the straight line connecting the _L 1 _{S 1,} and _{L 2} and _{S 2} is the length of a straight line connecting includes a thickness direction of the quantum dot containing layer The level of moisture resistance and oxygen resistance of the surface in the vertical direction is shown. Moreover, although humidity and oxygen penetrate | invade also from the surface by the side of the thickness direction of a quantum dot content layer, the entrance of humidity and oxygen from this surface can be controlled by sealing part (B). S ₁ O and S ₂ O indicate the level of moisture resistance and oxygen resistance of the surface in the thickness direction of the quantum dot-containing layer.
That is, satisfying the relationship that S ₁ O is always L ₁ S ₁ or more and S ₂ O is always L ₂ S ₂ or more (satisfies the condition (3)) is on the thickness direction side of the quantum dot-containing layer. It shows that the level of moisture resistance and oxygen resistance of the surface tends to be equal to or higher than the level of moisture resistance and oxygen resistance of the surface in the direction perpendicular to the thickness direction of the quantum dot-containing layer. Therefore, by satisfying the condition (3), it is possible to suppress the deterioration of the quantum dots near the end face (edge region) on the thickness direction side of the quantum dot-containing layer before the other portions. Gradually taking on the color of primary light can be suppressed.

FIG. 7 is a cross-sectional view of the quantum dot sheet cut in a direction parallel to the thickness direction and perpendicular to the end surface on the thickness direction side of the laminate (A), and an arbitrary curve M required for calculation of the condition (3) The point S is the end S ₁ on the light transmissive substrate (i) side of the line S, the end S ₂ on the light transmissive substrate (ii) side of the line S, and the light transmissive substrate of the line L ( end L ₁ of the i) _side, and is obtained by filling the end L ₂ information such as the light-transmitting substrate (ii) side of the line L.

In the sealing part (B), the cross-sectional shape of the sealing part (B) when the quantum dot sheet is cut in a direction parallel to the thickness direction and perpendicular to the end face on the thickness direction side of the laminate (A) is as follows. It is preferable to satisfy (4).
<Condition (4)>
When a perpendicular line is drawn from an arbitrary point O on the curve M to the line L and the maximum length of the perpendicular line is defined as the height h of the cross-sectional shape, the relationship of 60 μm ≦ h ≦ 240 μm is satisfied.

By setting the height h of the cross-sectional shape to 60 μm or more, the humidity and oxygen are prevented from entering from the surface on the thickness direction side of the quantum dot-containing layer, and the vicinity of the end surface (edge region) on the thickness direction side of the quantum dot-containing layer It is easy to suppress deterioration of the quantum dots. Moreover, by setting the height h of the cross-sectional shape to 240 μm or less, it is possible to easily suppress the breakage or peeling of the sealing portion (B).
The condition (4) more preferably satisfies the relationship of 70 μm ≦ h ≦ 200 μm, and more preferably satisfies the relationship of 80 μm ≦ h ≦ 180 μm.

In the sealing part (B), it is preferable that the cross-sectional shape of the sealing part (B) when the quantum dot sheet is cut in a direction parallel to the thickness direction satisfies the following condition (5).
<Condition (5)>
When the length of the line formed by the end surface on the thickness direction side of the laminate (A) is D and the length of the line L is d, the relationship of 0.8 ≦ d / D ≦ 1.0 is satisfied. .

By setting d / D to 0.8 or more, humidity and oxygen from the thickness direction side surface of the quantum dot-containing layer are suppressed, and the vicinity of the end surface (edge region) on the thickness direction side of the quantum dot-containing layer is suppressed. It is possible to easily suppress the deterioration of the quantum dots.
Condition (5) more preferably satisfies the relationship of 0.9 ≦ d / D ≦ 1.0, and more preferably d / D = 1.0.

  Conditions (1) to (5) are: a scanning transmission electron microscope (STEM) showing a cross section when the quantum dot sheet is cut in a direction parallel to the thickness direction and perpendicular to the end surface on the thickness direction side of the laminate (A). Can be calculated based on the image taken using the. The STEM acceleration voltage is preferably 10 kv to 30 kV, and the magnification is preferably 100 to 7000 times.

Light transmissive resin The sealing portion (B) preferably contains a light transmissive resin.
Examples of the light transmissive resin include a thermoplastic resin, a cured product of a thermosetting resin composition, and a cured product of an ionizing radiation curable resin composition. Among these, from the viewpoint of improving the strength of the sealing portion (B) and preventing breakage, a cured product of a thermosetting resin composition and a cured product of an ionizing radiation curable resin composition are preferable, and an ionizing radiation curable resin. A cured product of the composition is more preferable.

  The sealing portion (B) may be formed of a light transmissive resin alone, but may contain particles, phosphors, and the like described later. The ratio of the light transmissive resin to the total solid content constituting the sealing part (B) is preferably 50 to 100% by mass, more preferably 60 to 99% by mass, and 75 to 99% by mass. More preferably it is.

The thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that is cured by heating.
Examples of the thermosetting resin include acrylic resin, urethane resin, phenol resin, urea melamine resin, epoxy resin, unsaturated polyester resin, and silicone resin. In the thermosetting resin composition, a curing agent is added to these curable resins as necessary.

The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter also referred to as “ionizing radiation curable compound”). Examples of the ionizing radiation curable functional group include an ethylenically unsaturated bond group such as a (meth) acryloyl group, a vinyl group, and an allyl group, an epoxy group, and an oxetanyl group.
In the present specification, “(meth) acryloyl group” refers to methacryloyl group and acryloyl group, and “(meth) acrylate” refers to methacrylate and acrylate. In the present specification, “ionizing radiation” means an electromagnetic wave or charged particle beam having an energy quantum capable of polymerizing or cross-linking molecules, and usually ultraviolet (UV) or electron beam (EB) is used. In addition, electromagnetic waves such as X-rays and γ-rays, and charged particle beams such as α-rays and ion beams can also be used.
When the ionizing radiation curable compound is an ultraviolet curable compound, the ionizing radiation curable composition preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator.

The light-transmitting resin preferably has a refractive index of 1.49 or more, and more preferably 1.52 or more. By setting the refractive index of the light-transmitting resin to 1.49 or more, primary light and secondary light can be easily totally reflected on the curved surface of the sealing portion (B), and primary on the curved surface of the sealing portion (B). The reflectance of light and secondary light can be increased. That is, by setting the refractive index of the light-transmitting resin to 1.49 or more, primary light and secondary light leaking from the end face of the laminate (A) can easily return to the laminate (A) side, and the edge region It is possible to easily suppress the coloring of the primary light.
In the present invention, the refractive index is determined by light having a wavelength of 450 nm. The refractive index of the light transmissive resin can be measured by the Abbe method.

The light-transmitting resin preferably has a water vapor transmission rate of 100 g / m ² / day or less, and more preferably 30 g / m ² / day or less, from the viewpoint of suppressing deterioration of the quantum dots.
A water vapor transmission rate of the light-transmitting resin is such that a sample having a thickness of 100 μm composed of 100% by weight of the light-transmitting resin is prepared, and a constant temperature and humidity apparatus is used in accordance with the cup method of JIS Z 0208: 1976. Can be measured as Condition B (40 ° C., 90% RH).
As the resin having a water vapor transmission rate of 100 g / m ² / day or less, an organic EL sealing resin can be used. In general, a resin having a small number of unsaturated bonds or a small number of hydroxyl groups tends to have a low water vapor transmission rate.

The particle sealing part (B) may contain particles in addition to the light-transmitting resin.
In addition, the particle | grains in a sealing part (B) are the concepts which do not contain the fluorescent substance mentioned later. That is, the particles in the sealing portion (B) do not include those in which electrons are excited by absorbing light and the excess energy is released as an electromagnetic wave when it returns to the ground state.

The particles are preferably any one or more particles selected from the following (a) to (c).
(A) Hollow particles (b) Metal particles or metal coating particles (c) When the refractive index of the light-transmitting resin is n ₁ and the refractive index of the particles is n ₂ , a relationship of 1.10 ≦ n ₂ / n ₁ Satisfy the particles.

Since the particles (a) to (c) have high reflectivity, the primary light and the secondary light leaking from the end face of the laminate (A) can be easily returned to the laminate (A), and the edge It is possible to easily suppress the region from being colored with primary light.
Among the particles (a) to (c), (a) hollow particles that have high reflectivity and can suppress the color of the particles themselves are suitable.

  As hollow particles of (a), acrylic resin, urethane resin (polyurethane), polyethylene resin, polypropylene resin, polycarbonate resin, polyvinyl chloride resin, melamine resin, nylon resin (polyamide resin), polystyrene resin, styrene-acrylic copolymer Combined resin, polyester resin, polybutadiene resin, polyisobutylene resin, polyacrylamide resin, polyvinyl alcohol resin, polyvinylidene chloride resin, polymaleic anhydride resin, polyvinylidene fluoride resin, polyacrylonitrile resin, polyvinyl acetate resin, polyethylene terephthalate resin, etc. Resin hollow beads formed from the above resin; inorganic hollow beads formed from an inorganic compound such as glass.

Examples of the metal particles (b) include particles formed from metals such as aluminum, gold, silver, and copper. Examples of the metal coating particles include general-purpose resin particles and those obtained by coating the surfaces of inorganic particles with the aforementioned metal.
As the particles (c), among general-purpose resin particles and inorganic particles, particles satisfying the relationship of 1.10 ≦ n ₂ / n ₁ can be used. Particles satisfying the relationship of 1.1 ≦ n ₂ / n ₁ differ depending on the type of light-transmitting resin and cannot be generally stated. However, high refractive index particles such as alumina, zirconia, and titania tend to satisfy the relationship. The particles (c) more preferably satisfy the relationship of 1.15 ≦ n ₂ / n ₁ , and more preferably satisfy the relationship of 1.18 ≦ n ₂ / n ₁ .

  Further, from the viewpoint of suppressing the deterioration of the quantum dots, the particles preferably have a low water vapor transmission rate or oxygen transmission rate. Examples of the particles having a low water vapor transmission rate and low oxygen transmission rate include alumina and silica.

The average particle diameter of the particles is preferably 0.3 to 20 μm, and more preferably 1 to 10 μm.
The average particle diameter of the particles in the sealing portion (B) can be calculated by the following operations (1) to (3).
(1) The transmission observation image of a sealing part (B) is imaged with an optical microscope. The magnification is preferably 500 to 2000 times.
(2) Ten arbitrary particles are extracted from the observed image, and the particle diameter of each particle is calculated. The particle diameter is measured as a distance between straight lines in a combination of two straight lines that maximizes the distance between the two straight lines when the cross section of the particle is sandwiched between two parallel straight lines.
(3) The same operation is performed five times on the observation image of another screen of the same sample, and the value obtained from the number average of the particle diameters for a total of 50 particles is taken as the average particle diameter of the particles.
The “average particle diameter of phosphor” and “average particle diameter of internal diffusion particles of quantum dot-containing layer”, which will be described later, can also be calculated in accordance with the above work.

  When the sealing part (B) contains a light-transmitting resin and particles, the mass ratio of the light-transmitting resin and the particles is preferably 99.9: 0.1 to 60:40, and 99: 1 More preferably, it is ˜80: 20.

The phosphor sealing portion (B) may contain a phosphor in addition to the light transmissive resin.
In addition, the fluorescent substance in a sealing part (B) says that an average particle diameter is 0.1 micrometer or more. The quantum dots to be described later have a size equal to or less than the Bohr radius of the exciton of the compound semiconductor (although it cannot be generally stated, the average particle size is 20 nm or less). That is, the phosphor and the quantum dot can be distinguished by a difference in particle diameter, and further, can be distinguished by a difference in emission based on a difference in particle diameter (emission efficiency, emission wavelength width).
Since the phosphor in the sealing part (B) has a much larger average particle diameter than the quantum dot as described above, when the phosphor and the quantum dot are the same amount, the surface area of the phosphor is that of the quantum dot. Much smaller than the surface area. For this reason, the phosphor is more resistant to humidity and oxygen than the quantum dots, and is less likely to deteriorate with time even in the sealing portion (B).

  The average particle size of the particles is preferably 0.1 to 30 μm, and more preferably 1 to 10 μm.

As the phosphor, one kind of phosphor may be used alone, or two or more kinds of phosphors may be used.
In addition, it is preferable that the phosphor has a light emission color of one kind of phosphor or a composite color of light emission of two or more kinds of phosphors that is complementary to the peak wavelength of the primary light. By using a phosphor whose complementary color at the peak wavelength of the primary light is visible to humans, it is possible to easily suppress the edge region of the quantum dot sheet from being colored with the primary light. If the wavelength complementary to the peak wavelength of the primary light overlaps with the absorption wavelength of the color filter, if the wavelength corresponding to the complementary color is emitted by the emission of one type of phosphor, the effectiveness of the phosphor is greatly reduced. . For this reason, when the wavelength complementary to the peak wavelength of the primary light overlaps with the absorption wavelength of the color filter, it is configured so that humans can visually recognize the complementary color by combining the emission of two or more phosphors. Is preferred.
The complementary color is a color that becomes white when mixed, and the colors on both sides passing through the white point in the CIE chromaticity diagram have a complementary color relationship.

Examples of the phosphor include sulfide phosphors, oxide phosphors, nitride phosphors, fluoride phosphors, YAG phosphors, sialon phosphors, and the like.
Examples of sulfide-based phosphors include CaS: Eu, SrS: Eu, SrGa ₂ S ₄ : Eu, CaGa ₂ S ₄ : Eu, (Sr, Ca, Ba, Mg) Ga ₂ S ₄ : Eu, (Sr, Ca Ba) S: Eu, Y ₂ O ₂ S: Eu, La ₂ O ₂ S: Eu, Gd ₂ O ₂ S: Eu, and the like. Examples of oxide phosphors include (Ba, Sr) ₃ SiO ₅ : Eu, (Ba, Sr) ₂ SiO ₄ : Eu, Tb ₃ Al ₅ O ₁₂ : Ce, and Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce. Is mentioned. Examples of the nitride phosphor include Ca ₂ Si ₅ N ₈ : Eu, Sr ₂ Si ₅ N ₈ : Eu, Ba ₂ Si ₅ N ₈ : Eu, (Ca, Sr, Ba) ₂ Si ₅ N ₈ : Eu, Ca _x (Al, Si) ₁₂ (O, N) ₁₆ : Eu (0 <x ≦ 1.5), CaSi ₂ O ₂ N ₂ : Eu, SrSi ₂ O ₂ N ₂ : Eu, BaSi ₂ O ₂ N _{2 : Eu, (Ca, Sr,} Ba) Si 2 O 2 N 2: Eu, CaAl 2 Si 4 N 8: Eu, CaSiN 2: Eu, CaAlSiN 3: Eu and the like. Examples of the fluoride-based phosphor include K ₂ TiF ₆ : Mn ⁴⁺ , Ba ₂ TiF ₆ : Mn ⁴⁺ , Na ₂ TiF ₆ : Mn ⁴⁺ , K ₃ ZrF ₇ : Mn ⁴⁺ , K ₂ SiF ₆ : Mn ^{4+ and the} like. It is done. Examples of the YAG phosphor include (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce. Examples of the sialon-based phosphor include Lu (Si, Al) ₁₂ (O, N) ₁₆ : Eu.
In the description of the phosphor material, the description before the symbol “:” indicates the base material, and the subsequent description indicates the activator.

  When the sealing part (B) contains a light-transmitting resin and a phosphor, the mass ratio of the light-transmitting resin and the phosphor is preferably 90:10 to 99.95: 0.05, 90 : 10-99.9: 0.1 is more preferable.

The sealing part (B) can be formed by the following method, for example.
<Method for forming sealing portion (B)>
(1) The process of preparing the "sealing part (B) formation composition" formed by mixing the material which comprises a sealing part (B).
(2) A step of discharging the composition by a liquid fixed amount discharge device (dispenser) toward the end surface on the thickness direction side of the laminate (A).
(3) A step of drying and curing the composition as necessary.

The 20 ° C. viscosity of the composition for forming a sealing part (B) is preferably 0.1 to 100 Pa · s, more preferably 0.4 to 10 Pa · s, and 0.6 to 8 Pa · s. More preferably, it is s. By setting the viscosity of the composition for forming the sealing part (B) in the above range, the surface tension acts appropriately on the composition while suppressing dripping of the composition, and the sealing part (B) The shape can be easily within the range of the above-described embodiment.
The viscosity of the composition for forming the sealing part (B) can be adjusted by the molecular weight of the resin, the content of the particles or phosphor, the content ratio of the solvent, and the like.

The composition for forming the sealing part (B) is preferably dried and cured quickly after being discharged from the nozzle of the dispenser from the viewpoint of making the shape of the sealing part (B) within the range of the embodiment described above. . For this reason, it is preferable that the dispenser is provided with a drying unit and / or a curing unit.
From the viewpoint of quickly drying the composition for forming the sealing part (B) and from the viewpoint of setting the viscosity of the composition within the above range, the composition for forming the sealing part (B) suppresses the content of the solvent as much as possible. It is preferable to do. Specifically, the content of the solvent in the composition for forming a sealing part (B) is preferably 10% by mass or less, more preferably 5% by mass or less, and 1% by mass or less. Is more preferable. Moreover, it is preferable that the composition for sealing part (B) formation does not contain a solvent from a viewpoint which does not require a drying process. In order to suppress the content of the solvent, the composition for forming the sealing part (B) preferably contains an ionizing radiation curable compound.
From the viewpoint of quickly curing the sealing part (B) forming composition, the sealing part (B) forming composition preferably includes an ionizing radiation curable compound.

  The sealing part (B) is a mold having a cavity corresponding to the sealing part (B), the mold is placed on the end surface of the laminate (A), and the sealing part (B ) It can also be formed by pouring the composition for formation and drying and curing the composition as necessary. In addition, when installing this type | mold in the whole area | region of the end surface of a laminated body (A), it is preferable to have an injection port in at least one part of this type | mold.

<Laminated body (A)>
The layered product (A) has a quantum dot that absorbs primary light and emits secondary light and a quantum dot-containing layer containing a binder resin on one surface and a light transmissive substrate (i) on the other surface. Having a conductive substrate (ii).

Quantum dot-containing layer The quantum dot-containing layer includes a quantum dot that absorbs primary light and emits secondary light and a binder resin.
As quantum dots, the first quantum dots that absorb primary light having a wavelength corresponding to blue and emit secondary light having a wavelength corresponding to red, and the primary light that absorbs primary light having a wavelength corresponding to blue correspond to green It is preferable that at least one second quantum dot that emits secondary light having a wavelength to be emitted is included, and it is more preferable that both the first quantum dot and the second quantum dot are included.
The primary light having a wavelength corresponding to blue preferably has a peak wavelength in the range of 380 to 480 nm, and more preferably has a peak wavelength of 450 nm. The secondary light having a wavelength corresponding to green preferably has a peak wavelength in the range of 495 to 570 nm, and more preferably has a peak wavelength of 528 nm. The secondary light having a wavelength corresponding to red preferably has a peak wavelength in the range of 620 to 750 nm, and more preferably has a peak wavelength of 637 nm.

The quantum dots (first quantum dot and second quantum dot) will be described below.
Quantum dots are nanometer-sized fine particles of semiconductors that have specific optical and electrical properties due to the quantum confinement effect (quantum size effect) in which electrons and excitons are confined in small crystals of nanometer size. It exhibits properties and is also called semiconductor nanoparticles or semiconductor nanocrystals.
The quantum dot is a semiconductor nanometer-sized fine particle and is not particularly limited as long as it is a material that produces a quantum confinement effect (quantum size effect). For example, as described above, there are semiconductor fine particles whose emission color is regulated by their own particle diameter and semiconductor fine particles having a dopant. As the quantum dots in the present invention, both semiconductor fine particles whose emission color is regulated by their own particle diameter and semiconductor fine particles having a dopant can be used, and excellent color purity can be obtained.
As described above, the quantum dots are clearly distinguished from the phosphors by the difference in emission (emission efficiency, emission wavelength width) based on the difference in particle diameter and particle diameter.

Quantum dots have different emission colors depending on their particle diameters. For example, in the case of quantum dots composed only of a core made of CdSe, the particle diameters are 2.3 nm, 3.0 nm, 3.8 nm, 4 nm, The peak wavelengths of the fluorescence spectrum at .6 nm are 528 nm, 570 nm, 592 nm, and 637 nm. That is, the particle diameter of the quantum dot that emits secondary light having a peak wavelength of 637 nm is 4.6 nm, and the particle diameter of the quantum dot that emits secondary light having a peak wavelength of 528 nm is 2.3 nm.
The quantum dot-containing layer may contain quantum dots that emit secondary light having a wavelength corresponding to red and quantum dots other than quantum dots that emit secondary light having a wavelength corresponding to green.
The content of the quantum dots is appropriately adjusted according to the thickness of the quantum dot-containing layer, the light recycling rate in the backlight, the target color, and the like. If the thickness of a quantum dot content layer is the range mentioned below, the content of a quantum dot is about 0.01-1.0 mass part to 100 mass parts of binder resin of a quantum dot content layer.

Specifically, the core material of the quantum dot includes MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS II-VI group semiconductor compounds such as HgSe and HgTe, III- such as AlN, AlP, AlAs, AlSb, GaAs, GaP, GaN, GaSb, InN, InAs, InP, InSb, TiN, TiP, TiAs and TiSb Examples thereof include semiconductor compounds such as group V semiconductor compounds, group IV semiconductors such as Si, Ge and Pb, or semiconductor crystals containing semiconductors. Alternatively, a semiconductor crystal including a semiconductor compound containing three or more elements such as InGaP can be used.
Further, as a quantum dot composed of semiconductor fine particles having a dopant, a semiconductor crystal obtained by doping the semiconductor compound with a cation of a rare earth metal such as Eu ³⁺ , Tb ³⁺ , Ag ⁺ , or Cu ⁺ or a cation of a transition metal is used. It can also be used.
The material used as the core of the quantum dot is a semiconductor crystal such as CdS, CdSe, CdTe, InP, InGaP, etc. from the viewpoints of ease of production, controllability of the particle diameter to obtain light emission in the visible range, and fluorescence quantum yield. Is preferred.

The quantum dot may be composed of one kind of semiconductor compound or may be composed of two or more kinds of semiconductor compounds, for example, a core made of a semiconductor compound and a shell made of a semiconductor compound different from the core. It may have a core-shell type structure.
When a core-shell quantum dot is used, the semiconductor that constitutes the shell uses a material with a higher band gap than the semiconductor compound that forms the core so that excitons are confined in the core. Can be increased.
Examples of the core-shell structure (core / shell) having such a bandgap relationship include CdSe / ZnS, CdSe / ZnSe, CdSe / CdS, CdTe / CdS, InP / ZnS, Gap / ZnS, Si / ZnS, Examples include InN / GaN, InP / CdSSe, InP / ZnSeTe, InGaP / ZnSe, InGaP / ZnS, Si / AlP, InP / ZnSTe, InGaP / ZnSTe, and InGaP / ZnSSe.

The size of the quantum dot may be appropriately controlled depending on the material constituting the quantum dot so that light having a desired wavelength can be obtained. As the particle size of the quantum dot decreases, the energy band gap increases. That is, as the crystal size decreases, the light emission of the quantum dots shifts to the blue side, that is, to the high energy side. Therefore, by changing the size of the quantum dot, the emission wavelength can be adjusted over the entire wavelength range of the ultraviolet region, the visible region, and the infrared region.
In general, the average particle size of the quantum dots is 20 nm or less, preferably 0.5 to 20 nm, and more preferably 1 to 10 nm.
The shape of the quantum dot is not particularly limited, and may be, for example, a spherical shape, a rod shape, a disk shape, or other shapes. When the particle dot is not spherical, the particle diameter of the quantum dot can be a true spherical value having the same volume.
The quantum dot may be coated with a resin. Quantum dots coated with resin, the refractive index of the binder resin of the quantum dot containing layer and n _A, the refractive index of the resin for covering the quantum dot (coating resin) upon the n _B, is n B _/ n _A It is preferable to satisfy the relationship of 1.02 or more or 0.98 or less. A quantum dot coated with a resin can improve the durability of the quantum dot. Moreover, when the refractive index of binder resin and the refractive index of coating resin satisfy | fill the said relationship, the quantum dot coat | covered with resin can serve as the effect | action of the internal diffusion particle mentioned later.

  Information such as the particle diameter, shape, and dispersion state of the quantum dots can be obtained by a transmission electron microscope (TEM). In addition, the crystal structure and particle diameter of the quantum dots can be obtained by X-ray crystal diffraction (XRD). Furthermore, the information regarding the particle diameter and surface of a quantum dot can also be obtained by an ultraviolet-visible (UV-Vis) absorption spectrum.

Binder resin Examples of the binder resin of the quantum dot-containing layer include thermoplastic resins, cured products of thermosetting resin compositions, and cured products of ionizing radiation curable resin compositions. Among these, from the viewpoint of durability, a cured product of the thermosetting resin composition and a cured product of the ionizing radiation curable resin composition are preferable, and a cured product of the ionizing radiation curable resin composition is more preferable.

The thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that is cured by heating.
Examples of the thermosetting resin include acrylic resin, urethane resin, phenol resin, urea melamine resin, epoxy resin, unsaturated polyester resin, and silicone resin. In the thermosetting resin composition, a curing agent is added to these curable resins as necessary.

  The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter also referred to as “ionizing radiation curable compound”). Examples of the ionizing radiation curable functional group include an ethylenically unsaturated bond group such as a (meth) acryloyl group, a vinyl group, and an allyl group, and an epoxy group and an oxetanyl group. Among them, an ethylenically unsaturated bond group is preferable. . Of the ethylenically unsaturated bond groups, a (meth) acryloyl group is preferred. Hereinafter, an ionizing radiation curable compound having a (meth) acryloyl group is referred to as a (meth) acrylate compound.

The ionizing radiation curable compound may be a monofunctional ionizing radiation curable compound having only one of the above functional groups, or may be a polyfunctional ionizing radiation curable compound having two or more of the above functional groups. Or a mixture thereof.
The ionizing radiation curable compound may be a monomer, an oligomer, a low molecular weight polymer, or a mixture thereof.
Among the ionizing radiation curable compounds, the monofunctional monomer can suppress the polymerization shrinkage and improve the flatness of the quantum dot sheet, and improve the adhesion of the quantum dot-containing layer to improve the initial stage and time of the quantum dot sheet. It is suitable at the point which suppresses a serious function fall. In particular, when the thickness of the quantum dot-containing layer is thick, the above-described effect is remarkable when a monofunctional monomer is used.
In addition, when the adhesion of the quantum dot-containing layer is improved by using a monofunctional monomer, the quantum dot-containing layer and a member positioned above and below the quantum dot-containing layer (for example, a light-transmitting group) without using an adhesive layer The material (i) and the light transmissive substrate (ii)) can be brought into close contact with each other. That is, by using a monofunctional monomer to improve the adhesion of the quantum dot-containing layer, the configuration of the quantum dot sheet can be easily symmetric with respect to the thickness direction about the quantum dot-containing layer. Further, without interposing the adhesive layer, the quantum dot-containing layer and the members (for example, the light-transmitting substrate (i) and the light-transmitting substrate (ii)) positioned above and below the quantum dot-containing layer are in close contact with each other. By making it, the moisture resistance and oxygen resistance of a quantum dot can be improved.
The proportion of the monofunctional monomer in the total ionizing radiation curable compound is preferably 40% by mass or more, more preferably 60% by mass or more, further preferably 80% by mass or more, and 90% by mass or more. More preferably, it is most preferable that it is 100 mass%.

  In addition, since the quantum dots are vulnerable to humidity, it is preferable to use as the main component an ionizing radiation curable compound that does not have a hydroxyl group in the molecule. Specifically, the ratio of the ionizing radiation curable compound having no hydroxyl group in the molecule to the total ionizing radiation curable compound is preferably 80% by mass or more, more preferably 90% by mass or more, and 100 More preferably, it is mass%.

  Examples of ionizing radiation curable compounds that do not contain a hydroxyl group in the molecule include ethyl (meth) acrylate, butyl (meth) acrylate, ethylhexyl (meth) acrylate, phenoxyethyl (meth) acrylate, octyl (meth) acrylate, and isononyl (meth). Monofunctional (meth) acrylate compounds such as acrylate and dicyclopentenyl (meth) acrylate, pentaerythritol tetra (meth) acrylate, 1,6-hexanediol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tri Propylene glycol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate DOO, dipentaerythritol hexa (meth) acrylate, pentaerythritol ethoxy tetra (meth) acrylate, ditrimethylolpropane tetra (meth) polyfunctional (meth) acrylate compounds such as acrylate.

  The ionizing radiation curable compound preferably has a total carbon number of 8 or more from the viewpoint of improving hydrophobicity and improving the moisture resistance of the quantum dots. In consideration of the adhesion of the quantum dot-containing layer in addition to the moisture resistance, the total number of carbon atoms of the ionizing radiation curable compound is more preferably 8-20. For example, examples of the monofunctional (meth) acrylate monomer having 8 to 20 carbon atoms include ethylhexyl (meth) acrylate, octyl (meth) acrylate, isononyl (meth) acrylate, and the like.

The molecular weight of the ionizing radiation curable compound is preferably 100 to 2000, more preferably 120 to 1000, and still more preferably 150 to 500. When the molecular weight of the ionizing radiation curable compound is 100 or more, it is possible to easily prevent dripping during production, and when the molecular weight is 2000 or less, the pressure when the quantum dot-containing layer is bonded to another layer Thus, the thickness of the quantum dot-containing layer can be easily made uniform.
When a monofunctional monomer is used as the ionizing radiation curable compound, the molecular weight of the monofunctional monomer is 100 from the viewpoint of preventing dripping at the time of production, uniforming the thickness of the quantum dot-containing layer, and adhesion of the quantum dot-containing layer. It is preferable that it is -500, It is more preferable that it is 120-400, It is further more preferable that it is 150-250.

When the ionizing radiation curable compound is an ultraviolet curable compound, the ionizing radiation curable composition preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator.
Examples of the photopolymerization initiator include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyldimethyl ketal, benzoylbenzoate, α-acyloxime ester, thioxanthones, and the like.
These photopolymerization initiators preferably have a melting point of 20 ° C. or lower. This is because when the melting point is 20 ° C. or lower, it can be easily dissolved at room temperature when added to the ionizing radiation curable compound at the time of production.
The photopolymerization accelerator can reduce polymerization inhibition by air during curing and increase the curing speed. For example, p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc. One or more selected may be mentioned.

Internal diffusing particles The quantum dot-containing layer may contain internal diffusing particles. By containing the internal diffusion particles, the primary light can be brought close to uniform diffusion, and the edge region of the quantum dot sheet can be easily suppressed from being colored with the primary light.

As the internal diffusion particles, both organic particles and inorganic particles can be used. Examples of the organic particles include particles made of polymethyl methacrylate, acrylic-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone resin, fluorine resin, polyester, and the like. . Examples of the inorganic fine particles include fine particles made of silica, alumina, zirconia, titania and the like.
Examples of the shape of the internal diffusion particles include a spherical shape, a disk shape, a rugby ball shape, and an indefinite shape.
The internal diffusion particles may be hollow particles, porous particles, or solid particles.

Further, as the internal diffusion particles, those in which n _B / n _A is 1.02 or more or 0.98 or less when the refractive index of the binder resin is n _A and the refractive index of the internal diffusion particles is n _B are used. It is preferable. n _B / n _A is a relative refractive index between the binder resin and the internal diffusion particles, and by making n _B / n _A 1.02 or more or 0.98 or less, it is possible to make primary light closer to uniform diffusion. it can. Further, by setting n _B / n _A to 1.02 or more or 0.98 or less, the probability that the primary light collides with the quantum dots increases, and the amount of quantum dots used can be reduced.
n _B / n _A is more preferably 1.10 or more or 0.95 or less, or 1.15 or more, from the viewpoint of strong diffusibility, suppression of light leakage of the polarizing plate, and balance of front luminance. More preferably, it is 0.90 or less.
The refractive index of the internal diffusion particles can be measured by the Becke method, and the refractive index of the binder resin can be measured by the Abbe method.

  The content of the internal diffusion particles is preferably 1 to 40 parts by mass and more preferably 3 to 30 parts by mass with respect to 100 parts by mass of the binder resin. By setting the content of the internal diffusion particles in the above range, light can be diffused to a high angle, while light leakage of the polarizing plate and a decrease in front luminance can be suppressed.

  The average particle size of the internal diffusion particles is preferably 10 μm or less, and more preferably 3 μm or less, from the viewpoint of increasing the number of particles per content and achieving diffusion uniformity. Note that the lower limit of the average particle size of the internal diffusion particles is about 0.1 μm.

  The thickness of the quantum dot-containing layer is preferably 10 to 200 μm, more preferably 20 to 150 μm, and still more preferably 30 to 130 μm. When the thickness of the quantum dot-containing layer is within this range, it is suitable for reducing the weight and thickness of the display device, and color unevenness due to fluctuation (manufacturing tolerance) of the thickness of the quantum dot-containing layer can be suppressed.

The quantum dot-containing layer is preferably formed in close contact with the layers positioned above and below the quantum dot-containing layer without using an adhesive layer. By setting it as this structure, while being able to make the structure of a quantum dot sheet | seat easy to make a structure symmetrical vertically in the thickness direction centering on a quantum dot content layer, it can make it easy to improve the moisture resistance and oxygen resistance of a quantum dot.
The layers positioned above and below the quantum dot-containing layer are preferably a light-transmitting substrate or a barrier layer from the viewpoint of improving the moisture resistance and oxygen resistance of the quantum dots.

  As shown in FIGS. 8 and 9, the laminate (A) preferably has a layer configuration that is vertically symmetrical about the quantum dot-containing layer in the thickness direction. By taking such a configuration, the planarity of the laminate (A) can be improved, and the uniformity of luminance within the surface of the quantum dot sheet can be improved. In addition, by taking such a configuration, strain concentrates on a specific interface among a plurality of interfaces (for example, interfaces between the quantum dot-containing layer and the light-transmitting substrate) existing in the laminate (A). It is possible to prevent the interfacial peeling.

Note that a layer configuration that is vertically symmetrical in the thickness direction means that the number of layers and the type of layers are the same up and down, and the thicknesses of the layers are substantially the same. In order to say that the thicknesses are substantially the same, the ratio of the thicknesses of the upper and lower layers in the relationship of interest is preferably in the range of 0.95 to 1.05, and in the range of 0.97 to 1.03. Is more preferable.
The thickness of each layer can be calculated, for example, by measuring the thickness at 20 locations from a cross-sectional image taken using a scanning transmission electron microscope (STEM) and calculating the average value of the 20 locations. The acceleration voltage of STEM is preferably 10 kv to 30 kV, and the magnification is preferably 100 to 7000 times. When the thickness is nano-order, the STEM magnification is preferably 50,000 to 300,000 times.
Further, it is preferable that the layers having a symmetrical relationship have substantially the same composition. In order to say that the compositions are substantially the same, 90% by mass or more of the constituent components of the layer are preferably the same, more preferably 95% by mass or more are the same, and 99% by mass or more are the same. Further preferred.

  The laminate (A) may have a three-layer structure of a quantum dot-containing layer, a light-transmitting substrate (i), and a light-transmitting substrate (ii). However, as shown in FIG. You may have. Examples of the other layers include a light transmissive substrate other than the light transmissive substrate (i) and the light transmissive substrate (ii), a barrier layer, a light diffusion layer, and an adhesive layer. In addition, also when it has another layer, it is preferable that a laminated body (A) is set as a vertically symmetrical layer structure in the thickness direction centering on a quantum dot content layer.

As shown in FIG. 8 and FIG. 9, the light-transmitting substrate laminate (A) 70 has a light-transmitting substrate (i) 21 on one surface of the quantum dot-containing layer 10 and a light-transmitting surface on the other surface. It has a substrate (ii) 22. As shown in FIGS. 8 and 9, it is preferable to contact the quantum dot-containing layer 10. Further, as shown in FIG. 9, the laminate (A) has other light transmissive properties on the side opposite to the quantum dot-containing layer of the transmissive substrate (i) 21 and the light transmissive substrate (ii) 22. You may have a base material.

The light-transmitting substrate is not particularly limited, but preferably has heat resistance and is excellent in smoothness, stiffness, and mechanical strength. Such transparent substrates include polyester, triacetyl cellulose (TAC), cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyether sulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal. , Polyether ketone, acrylic, polycarbonate, polyurethane, and amorphous olefin (Cyclo-Olefin-Polymer: COP).
Among these, from the viewpoint of mechanical strength, dimensional stability, and heat resistance, polyester (polyethylene terephthalate, polyethylene naphthalate) that has been stretched, particularly biaxially stretched, is preferable.

The thickness of the light-transmitting substrate is preferably 10 to 200 μm, more preferably 20 to 150 μm, and further preferably 30 to 100 μm, from the viewpoint of the balance between mechanical strength, stiffness, and thinning.
In addition to physical treatment such as corona discharge treatment and oxidation treatment, a coating called an anchor agent or a primer may be applied to the surface of the light transmissive substrate in advance in order to improve adhesion.

Barrier layer The barrier layer has a role of improving the moisture resistance and oxygen resistance of the quantum dots.
The barrier layer is preferably formed on the light transmissive substrate (i), the light transmissive substrate (ii), or other light transmissive substrate.

The barrier layer is preferably a layer made of an inorganic substance or an inorganic oxide, and examples thereof include an inorganic or inorganic oxide vapor-deposited film and an inorganic alkoxide hydrolyzed film. From the viewpoint of moisture resistance and oxygen resistance, the barrier layer is preferably an inorganic or inorganic oxide vapor deposition film.
The barrier layer can be formed by a known method using a known inorganic substance, inorganic oxide, inorganic alkoxide, and the like, and the composition and formation method are not particularly limited. The barrier layer may be a single layer or may have two or more layers. When two or more barrier layers are provided, each may have the same composition or a different composition.

The material of the deposited film is silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti). , Lead (Pb), zirconium (Zr), yttrium (Y), and the like, oxides thereof, and those in which an organic substance is blended.
The inorganic alkoxide that is a material of the hydrolyzed membrane is also called a metal alkoxide, and examples thereof include silicon alkoxide such as tetraalkoxysilane, titanium alkoxide, and aluminum alkoxide.

The thickness of the barrier layer is preferably from 5 to 1000 nm, more preferably from 10 to 700 nm, and more preferably from 10 to 500 nm, from the viewpoint of the balance between moisture resistance, oxygen resistance, cracking suppression and light transmittance. Further preferred. When the barrier layer is a deposited film, the thickness of the barrier layer is preferably 5 to 30 nm, more preferably 7 to 25 nm, and still more preferably 10 to 20 nm.
As a method for forming a vapor deposition film as a barrier layer, for example, a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method and an ion plating method, a plasma chemical vapor deposition method, a thermal chemical vapor deposition method, or the like. Examples thereof include a chemical vapor deposition method (CVD method) such as a growth method and a photochemical vapor deposition method.

Adhesive layer In order to laminate the layers constituting the laminate (A), an adhesive layer may be interposed between the layers. For example, in FIG. 9, the adhesive layer 50 is provided between the light transmissive substrate (i) 21 and the barrier layer 30, between the light transmissive substrate (ii) 22 and the barrier layer 30, and the like. .
The adhesive layer can be formed from a general-purpose pressure-sensitive adhesive (pressure-sensitive adhesive), a thermosetting adhesive, or an ionizing radiation curable adhesive.
The thickness of the adhesive layer is preferably 0.5 to 20 μm and more preferably 1 to 10 μm from the viewpoint of adhesive strength and thinning.

  Although the total thickness of a laminated body (A) is not specifically limited, It is about 100-700 micrometers.

Method for Producing Laminate (A) When the laminate (A) has a three-layer structure of a quantum dot-containing layer, a light transmissive substrate (i), and a light transmissive substrate (ii), a light transmissive substrate ( After applying a quantum dot-containing layer coating solution containing a quantum dot and a binder resin component that absorbs primary light and emits secondary light on one surface of i), and after forming a quantum dot-containing layer, A laminated body (A) can be manufactured by bonding the light-transmitting substrate (ii) on the layer.

When the laminate (A) has a quantum dot-containing layer, a light-transmitting substrate (i), a light-transmitting substrate (ii) and other layers and has a vertically symmetric structure in the thickness direction, the following steps ( It is preferable to manufacture by a)-(c).
(A) A step of laminating the light transmissive substrate (i) and other layers to obtain a laminate a1, and laminating the light transmissive substrate (ii) and other layers to obtain a laminate a2.
(B) A quantum dot-containing layer coating liquid containing a quantum dot that absorbs primary light and emits secondary light and a binder resin component on one surface of one of the laminates a1 and a2 The process of apply | coating and forming a quantum dot content layer.
(C) The quantum dot-containing layer is a layered body in which the quantum dot-containing layer is not formed in step (b), and the surface on the quantum dot-containing layer side of the laminate in which the quantum dot-containing layer is formed in step (b). The process of laminating | stacking so that it may become a layer structure symmetrical up and down in the thickness direction centering on.

The layered product a1 and the layered product a2 produced in the step (a) have the same number of layers, and the symmetrical layer thickness and composition are substantially the same.
As the binder resin component in the step (b), any of a thermoplastic resin, a cured product of a thermosetting resin composition, an ionizing radiation curable resin composition, or a mixture thereof can be used.

  In step (c), the laminate in which the quantum dot-containing layer is not formed in step (b) is bonded to the surface on the quantum dot-containing layer side of the laminate in which the quantum dot-containing layer is formed in step (b). In this case, as shown in FIG. 9, it is preferable to bond the layers without using an adhesive layer from the viewpoint of having a vertically symmetric configuration around the quantum dot-containing layer in the thickness direction.

When the binder resin component in the step (b) is an ionizing radiation curable resin composition, the following technique should be adopted in order to bond the two laminates without interposing an adhesive layer in the step (c). Is preferred.
First, the ionizing radiation curable resin composition preferably contains a monofunctional monomer.
Second, when forming the quantum dot-containing layer in the step (b), do not irradiate ionizing radiation, or suppress the irradiation amount of ionizing radiation and leave an uncured portion in the ionizing radiation curable resin composition. It is preferable that the ionizing radiation curable resin composition is cured by irradiating ionizing radiation after the step (c).
Combining the first method and the second method is preferable in that the workability of bonding the two laminates in the step (c) without any adhesive layer is further improved.

Transmittance The total light transmittance of JIS K7361-1: 1997 of the laminate (A) is not particularly limited, but is usually about 40% or more.

[Backlight]
The backlight of the present invention includes at least one light source that emits primary light, an optical plate disposed adjacent to the light source, for guiding or diffusing light, and a quantum disposed on a light output side of the optical plate. In a backlight including a dot sheet, the quantum dot sheet is the above-described quantum dot sheet of the present invention.

  As an example of the backlight of the present invention, an edge light type backlight as shown in FIG. 10 or a direct type backlight as shown in FIG. 11 can be adopted.

  The optical plate 120 used in the edge light type backlight of FIG. 10 is an optical member for guiding the primary light emitted from the light source 110, and is a so-called light guide plate. The light guide plate has, for example, a substantially flat shape formed such that at least one surface is a light incident surface and one surface substantially orthogonal to the light incident surface is a light emitting surface.

  In the edge light type backlight, it is preferable that the sealing portion (B) is formed at least on the end surface on the side where the light source 110 is located.

  The light guide plate is mainly made of a matrix resin selected from highly transparent resins such as polymethyl methacrylate. The light guide plate may be added with resin particles having a refractive index different from that of the matrix resin as required. Each surface of the light guide plate may have a complicated surface shape instead of a uniform plane, and may be provided with a dot pattern or the like.

  The optical plate 120 used in the direct type backlight of FIG. 11 is an optical member (light diffusing material) having light diffusibility for making the pattern of the light source 110 difficult to see. Examples of the light diffusing material include a milky white resin plate having a thickness of about 1 to 3 mm.

  In addition to the light source, optical plate, and quantum dot sheet described above, the edge light type and direct type backlights include a reflection plate, a light diffusion film, a prism sheet, a brightness enhancement film (BEF), and a reflection type depending on the purpose. One or more members selected from a polarizing film (DBEF) and the like may be provided. The reflecting plate is disposed on the side opposite to the light emitting surface side of the optical plate. The light diffusion film, the prism sheet, the brightness enhancement film, and the reflective polarizing film are disposed on the light exit surface side of the optical plate. By having a configuration including one or more members selected from a reflector, a light diffusion film, a prism sheet, a brightness enhancement film, a reflective polarizing film, etc., a backlight having excellent balance of front luminance, viewing angle, etc. Can do.

In the edge light type and direct type backlights, the light source 110 is a light emitter that emits primary light, and it is preferable to use a light emitter that emits primary light having a wavelength corresponding to blue. The primary light having a wavelength corresponding to blue preferably has a peak wavelength in the range of 380 to 480 nm, and more preferably has a peak wavelength of 450 nm. The light source 110 is preferably an LED light source, more preferably a blue single-color LED light source, from the viewpoint that a device for installing a backlight can be simplified and miniaturized. The number of the light sources 110 is at least one, and a plurality of light sources 110 are preferable from the viewpoint of emitting sufficient primary light.
In addition, when only one of the first quantum dots and the second quantum dots is contained in the quantum dot-containing layer of the quantum dot sheet, in addition to the primary light source composed of a light emitter that emits primary light having a wavelength corresponding to blue. It is preferable to have an auxiliary light source. Specifically, when only the first quantum dot is contained in the quantum dot-containing layer, it is preferable to use a light emitter that emits light having a wavelength corresponding to green as an auxiliary light source. Moreover, when only the 2nd quantum dot is contained in a quantum dot content layer, it is preferable to use the light-emitting body which emits the light of the wavelength equivalent to red as an auxiliary light source.

  Since the backlight of the present invention uses the above-described quantum dot sheet of the present invention, the color of the edge region of the backlight and the angle dependency of the color can be improved.

[Liquid Crystal Display]
The liquid crystal display device of the present invention is a liquid crystal display device including a backlight and a liquid crystal panel, and the backlight is the above-described backlight of the present invention.

  FIG. 12 is a cross-sectional view showing an embodiment of the liquid crystal display device of the present invention. The liquid crystal display device 300 in FIG. 5 includes a backlight 200 and a liquid crystal panel 210. Further, the backlight 200 and the liquid crystal panel 210 are incorporated and fixed in the holder 220.

  The liquid crystal panel includes a polarizing plate (not shown) and a color filter (not shown). The liquid crystal panel is not particularly limited, and generally known liquid crystal panels for liquid crystal display devices can be used. For example, a liquid crystal panel having a general structure in which the upper and lower sides of the liquid crystal layer are sandwiched between glass plates, specifically, display types such as TN, STN, VA, IPS and OCB can be used.

  The polarizing plate is not particularly limited as long as it has desired polarization characteristics, and generally known polarizing plates can be used as a polarizing plate for a liquid crystal display device. Specifically, for example, a polyvinyl alcohol film is stretched, and a polarizing plate containing iodine is preferably used.

The color filter is not particularly limited. For example, a color filter that is generally known as a color filter of a liquid crystal display device can be used. The color filter is usually composed of transparent colored patterns of each color of red, green and blue, and each transparent colored pattern is composed of a resin composition in which a colorant is dissolved or dispersed, preferably pigment fine particles are dispersed. .
The color filter is formed by adjusting the ink composition colored in a predetermined color and printing it for each colored pattern, or a paint type photosensitive resin composition containing a colorant of a predetermined color The method of forming by a photolithographic method using a thing is mentioned.

  The display image of the liquid crystal display device is displayed in color as white light emitted from the backlight passes through the color filter. A liquid crystal display device can realize a display that is excellent in brightness and efficiency and generates a very clear color by using a color filter that matches a backlight spectrum of quantum dots.

  The liquid crystal panel may have a configuration in which an arbitrary layer is formed as a single layer or multiple layers on a color filter. The optional layer is not particularly limited. For example, the sensor layer for touch panel, hard coat layer, antistatic layer, low refractive index layer, high refractive index layer, antiglare layer, antifouling layer, antireflection layer, high dielectric Examples thereof include a body layer, an electromagnetic wave shielding layer, and an adhesive layer.

  Since the liquid crystal display device of the present invention uses the above-described backlight of the present invention, the color of the edge region of the display image and the angle dependency of the color can be improved.

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples. “Part” and “%” are based on mass unless otherwise specified. The refractive index is a refractive index with a wavelength of 450 nm unless otherwise specified.

1. Measurement and Evaluation of Physical Properties of Quantum Dot Sheet Measurement and evaluation of physical properties of quantum dot sheets and backlights of Examples and Comparative Examples were performed as follows. The results are shown in Table 1.

1-1. Cross-sectional shape of sealing part (B) Scanning the cross-section when the quantum dot sheet produced in “4” below is cut in a direction parallel to the thickness direction and perpendicular to the end surface on the thickness direction side of the laminate (A) Parameters (h / d, r _min / r _ave , r _max / r _ave , h, and d / D of conditions (1) to (5) based on an image taken using a transmission electron microscope (STEM) ) Was calculated. The STEM acceleration voltage was 2 kv and the magnification was 500 times.
In addition, Comparative Example 1 does not have a sealing part (B), and Comparative Examples 2 to 4 do not measure the cross-sectional shape of the sealing part (B) because the sealing part (B) is not curved. .

1-2. The color of the edge region The backlights of Examples 1 to 5 and Comparative Examples 1 to 4 prepared in “4” below were turned on, and the color (blueness) of the edge region of the backlight immediately after lighting was visually evaluated. . 20 subjects were evaluated based on the evaluation criteria of 1 point for those who were not concerned about the bluish color, 2 points for those that were slightly concerned about the bluish color, and 3 points for those that were very concerned about the bluishness. The average score was calculated. AA with an average score of 1.50 or less, “A” with an average score of more than 1.50 and 2.00 or less, and an average score of more than 2.00 and less than 2.50 Is “B”, and those having an average score of 2.5 or more are “C”.
In addition, since the edge part of the comparative example 3 was light-shielded with the aluminum tape, it was set as "-".

1-3. Suppression of deterioration of quantum dots The backlights of Examples 1 to 5 and Comparative Example 1 prepared in “4” below were turned on, and the degree of suppression of deterioration of the quantum dots was evaluated every predetermined time. Specifically, the backlight photo immediately after lighting is compared with the backlight photo after a lapse of a predetermined time, and the difference in color between the two photos is one that does not matter at all. 20 subjects evaluated the average score based on an evaluation standard that scored 2 points for those with slight worries and 3 points for those with severe color differences. AA with an average score of 1.50 or less, “A” with an average score of more than 1.50 and 2.00 or less, and an average score of more than 2.00 and less than 2.50 Is “B”, and those having an average score of 2.5 or more are “C”.

2. Fabrication of Quantum Dot Refer to the method described in the technical document “Journal of American Chemical Society. 2007, 129, 15432-15433”, and the InP / ZnS core-shell quantum dot (quantum dot A ), And InP / ZnS core-shell quantum dots (quantum dots B) having a fluorescence spectrum peak wavelength of 528 nm.

3. Production of Laminate (A) On one surface of a biaxially stretched PET film having a thickness of 12 μm, a thickness SiO _X was deposited by the PVD method to form an inorganic barrier layer having a thickness of 20 nm to obtain a barrier film. Next, on one surface of a 50 μm-thick biaxially stretched PET film, a light diffusion layer coating liquid having the following formulation was applied and dried so that the thickness after drying was 3 μm, and then irradiated with ultraviolet rays to form a light diffusion layer. Formed to obtain a light diffusion film. Next, a light diffusion film, a barrier film, and a biaxially stretched PET film having a thickness of 50 μm were laminated in the above order via an adhesive layer having a thickness of 3 μm to obtain a laminate a1 (see FIG. 9). The barrier film and the light diffusing film were bonded together so that the surfaces on the biaxially stretched PET film side of both faces each other. Next, a laminate b1 was obtained by the same operation as described above.
Next, a quantum dot-containing layer that has not been irradiated with ionizing radiation is applied to the surface of the laminated body a1 on the biaxially stretched PET film side by applying and drying a quantum dot-containing layer coating solution of the following formulation so that the thickness after drying is 100 μm Formed.
Subsequently, the quantum dot-containing layer that has not been irradiated with ionizing radiation and the biaxially stretched PET film side surface of the laminate b1 are bonded to face each other, and ultraviolet rays are irradiated from the light diffusion layer side of the laminate a1 to obtain ionizing radiation. Curing of the curable resin composition was advanced to obtain a laminate (A).

<Light diffusion layer coating solution a1>
・ Pentaerythritol triacrylate 30 parts (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30)
・ 70 parts of urethane acrylate (manufactured by Nippon Synthetic Chemical Co., Ltd., UV1700B)
-Photopolymerization initiator 5 parts (BASF, Irgacure 184)
・ Silicon-based leveling agent 0.1 part (Momentive Performance Materials, TSF4460)
・ 5 parts of urethane resin diffusion particles (average particle size 3μm)
・ 500 parts of diluted solvent

<Quantum dot content layer coating liquid b1>
-100 parts of isononyl acrylate (monofunctional monomer, refractive index 1.45)
-Photopolymerization initiator 5 parts (BASF, Irgacure 184)
・ Quantum dot A 0.2 part ・ Quantum dot B 0.2 part ・ Inner scattering particle 20 parts (true spherical alumina, average particle diameter 1.5 μm, refractive index 1.76)
・ Diluted solvent 5 parts

3. Production of quantum dot sheet (formation of sealing part (B))
[Example 1]
The laminate (A) was cut into a size of 7 cm in length and 12 cm in width. A dispenser A with an ultraviolet light source was prepared by attaching an ultraviolet light source to the moving nozzle of a dispenser (product name: SHOT MINI 100S) manufactured by Musashi Engineering. Fill the tank of the dispenser A with the sealing part (B) forming composition 1 (the viscosity of the composition 1 at 20 ° C .: 0.6 Pa · s) of the following formula, and set the temperature in the tank to 20 ° C. While moving the nozzle of A at a speed of 2 cm / s, the composition is discharged to the entire region of the end surface in the thickness direction of the laminated body (A) after cutting, and ultraviolet rays are irradiated from an ultraviolet light source provided immediately after the discharge to irradiate the composition. The composition was cured to form a sealing part (B), and the quantum dot sheet of Example 1 was obtained.
In addition, the peak wavelength of a blue LED which is a light source of a backlight described later is 450 nm, and the wavelength of a complementary color of the peak wavelength of the blue LED is about 569 nm. The phosphor mixture of the sealing part (B) forming composition 1 is composed of a red light emitting phosphor (Sr ₂ Si ₇ Al ₃ ON ₁₃ : Eu) and a green light emitting phosphor (Sr ₃ Si ₁₃ Al ₃ O ₂ N _21). : Eu), the complementary color can be visually recognized by humans. Therefore, the phosphor mixture of the sealing portion (B) forming composition 1 corresponds to “a phosphor in which the combined color of light emission of two or more phosphors is a complementary color of the peak wavelength of the primary light”.

<Sealing part (B) formation composition 1>
・ Ionizing radiation curable compound 100 parts (manufactured by Sekisui Chemical Co., Ltd., trade name: Photorec A-704)
(Water vapor transmission rate 80 g / m ² / day, refractive index 1.49)
-1 part of phosphor mixture (mixture of red light-emitting phosphor and green light-emitting phosphor, average particle diameter of 5 μm)
-20 parts of particles (spherical alumina, average particle size 1.5 μm, refractive index 1.76)

[Example 2]
The ionizing radiation curable compound (product name: Photorec A-704, manufactured by Sekisui Chemical Co., Ltd.) of the sealing part (B) forming composition 1 is changed to a type having a different viscosity of the company name, and the sealing part ( B) A quantum dot sheet of Example 2 was obtained in the same manner as in Example 1 except that the composition was changed to the forming composition 2 (viscosity of the composition 2 at 20 ° C .: 0.3 Pa · s).

[Example 3]
The ionizing radiation curable compound (product name: Photorec A-704, manufactured by Sekisui Chemical Co., Ltd.) of the sealing part (B) forming composition 1 is changed to a type having a different viscosity of the company name, and the sealing part ( B) A quantum dot sheet of Example 3 was obtained in the same manner as in Example 1 except that the composition was changed to the forming composition 3 (viscosity of the composition 3 at 20 ° C .: 0.5 Pa · s).

[Example 4]
The ionizing radiation curable compound (product name: Photorec A-704, manufactured by Sekisui Chemical Co., Ltd.) of the sealing part (B) forming composition 1 is changed to a type having a different viscosity of the company name, and the sealing part ( B) A quantum dot sheet of Example 4 was obtained in the same manner as in Example 1 except that the composition was changed to the forming composition 4 (viscosity of the composition 3 at 20 ° C .: 6.0 Pa · s).

[Example 5]
The ionizing radiation curable compound (product name: Photorec A-704, manufactured by Sekisui Chemical Co., Ltd.) of the sealing part (B) forming composition 1 is changed to a type having a different viscosity of the company name, and the sealing part ( B) A quantum dot sheet of Example 5 was obtained in the same manner as in Example 1 except that the composition was changed to the forming composition 5 (the viscosity of the composition 5 at 20 ° C .: 18.0 Pa · s).

[Comparative Example 1]
A laminate (A) cut to a size of 7 cm in length and 12 cm in width was used as the quantum dot sheet of Comparative Example 1.

[Comparative Example 2]
The laminate (A) was cut into a size of 7 cm in length and 12 cm in width. The entire region of the end face in the thickness direction of the laminated body (A) after cutting was sealed with a tape made of vinylidene chloride having a thickness of 100 μm to obtain a quantum dot sheet of Comparative Example 2.

[Comparative Example 3]
The laminate (A) was cut into a size of 7 cm in length and 12 cm in width. The entire region of the end face in the thickness direction of the laminated body (A) after cutting was sealed with an aluminum tape having a thickness of 100 μm to obtain a quantum dot sheet of Comparative Example 3.

[Comparative Example 4]
The laminate (A) was cut into a size of 7 cm in length and 12 cm in width. One end face of the four end faces in the thickness direction of the laminate (A) after cutting was sealed part forming composition 6 (the temperature of the sealing part forming composition 1 was 30 ° C., 30 ° C. (Viscosity: 0.1 Pa · s) After being pulled up, the composition was cured by irradiation with ultraviolet rays. The same operation was performed for the remaining three end faces, and a sealing portion was formed in the entire region of the end face in the thickness direction of the laminated body (A) after cutting, whereby a quantum dot sheet of Comparative Example 4 was obtained. FIG. 13 is an image diagram of a cross-sectional shape of the sealing portion of Comparative Example 4.

4). Production of backlight and liquid crystal display device A commercially available liquid crystal display device using a blue LED (peak wavelength: 450 nm) as a light source (7 inches diagonal, with a light source installed on one side of the short side) is disassembled, and a backlight is obtained. Was taken out. The backlight was an edge light type, and had a reflecting plate below the light guide plate, a light diffusion film and two prism sheets above the light guide plate. In the two prism sheets, the stripe lines are orthogonal to each other between the lower and upper sheets.
The light diffusion film is removed from the backlight, and the quantum dot-containing sheets of Examples 1 to 5 and Comparative Examples 1 to 4 are arranged between the light guide plate and the prism sheet, and Examples 1 to 5 and Comparative Example 1 are arranged. A backlight of ~ 4 was obtained.
Next, the backlights of Examples 1 to 5 and Comparative Examples 1 to 4 were returned to the places where the backlights of the disassembled liquid crystal display devices were installed, and the liquid crystal display devices of Examples 1 to 5 and Comparative Examples 1 to 4 were returned. Got.

From the results in Table 1, it can be confirmed that the quantum dot sheets, backlights, and liquid crystal display devices of Examples 1 to 5 can improve the color of the edge region. Moreover, it can also confirm that the quantum dot sheet | seat of Example 1-5, a backlight, and a liquid crystal display device can suppress deterioration of a quantum dot. Although not described in the table, even if a test is performed in which the quantum dot sheets of Examples 1 to 5 are vibrated left and right in a state where a load is applied to the sealing portion (B), The sealing part (B) was not easily broken or peeled off.
On the other hand, since the quantum dot sheet of Comparative Example 1 does not have a sealing portion, and the quantum dot sheets of Comparative Examples 2 and 4 have a curved shape, the edge region is improved in color compared to the Example. I can confirm that I can't. In addition, since the quantum dot sheet of Comparative Example 3 is a tape made of aluminum, the sealed area is excluded from the effective area of the backlight, and the area of the bezel has to be enlarged. there were.

10: Quantum dot-containing layer 21: Light-transmitting substrate (i)
22: Light transmissive substrate (ii)
23, 24, 25, 26: Other light-transmitting substrates 30: barrier layer 30a: barrier film 40: light diffusion layer 40a: light diffusion film 50: adhesive layer 60: laminate (A)
61: Laminate a1
62: Laminate a2
63: Thickness direction end face 90 of the laminate (A): Sealing part (B)
100: quantum dot sheet 110: light source 120: optical plate 130: reflector 140: prism sheet 200: backlight 210: liquid crystal panel 220: holder 300: liquid crystal display device

Claims (10)

  A light-transmitting substrate (i) is provided on one surface of a quantum dot-containing layer containing a quantum dot and a binder resin that absorbs primary light and emits secondary light, and a light-transmitting substrate (ii) is provided on the other surface. The laminate (A) having a sealing portion (B) formed on at least a part of the end surface on the thickness direction side of the laminate (A), the sealing portion (B) A quantum dot sheet having a curved shape that is convex on the side opposite to the laminate (A) with respect to the end face. The cross-sectional shape of the sealing part (B) when the quantum dot sheet is cut in a direction parallel to the thickness direction and perpendicular to the end surface on the thickness direction side of the laminate (A) satisfies the following condition (1). The quantum dot sheet according to claim 1.
<Condition (1)>
Of the lines constituting the outer frame of the cross-sectional shape, a line overlapping with a line formed by an end face on the thickness direction side of the laminate (A) is a line L, and the laminate L (A) side of the line L A curve M is an arcuate line that is located on the opposite side and forms the curved surface shape. When a perpendicular is drawn with respect to the line L from an arbitrary point O on the curve M, the maximum value of the length of the perpendicular is defined as the height h of the cross-sectional shape. Further, when the length of the line L is d, the relationship of 0.20 ≦ h / d ≦ 0.80 is satisfied. The quantum dot sheet according to claim 1 or 2, wherein a cross-sectional shape in the thickness direction of the sealing portion (B) satisfies the following condition (2).
<Condition (2)>
Of the lines constituting the outer frame of the cross-sectional shape, a line overlapping with a line formed by an end face on the thickness direction side of the laminate (A) is a line L, and the laminate L (A) side of the line L A curve M is an arcuate line that is located on the opposite side and forms the curved surface shape. Let N be the midpoint of the line L. An arbitrary point on the curve M is defined as O, and a straight line connecting the midpoint N and the arbitrary point O is defined as a straight line P. Let Q be the slope of the straight line P with respect to the line L. The arbitrary point O is moved along the curve M so that the inclination Q changes by 5 degrees from 5 degrees to 175 degrees, and the length r of the straight line P at each inclination is calculated. When the average length of 35 lengths r is r _ave , the minimum value of length r is r _min , and the maximum value of length r is r _max , r _min / r _ave is 0.40 or more. R _max / r _ave satisfies the relationship of 1.60 or less. The quantum dot sheet according to any one of claims 1 to 3, wherein a cross-sectional shape in the thickness direction of the sealing portion (B) satisfies the following condition (3).
<Condition (3)>
Of the lines constituting the outer frame of the cross-sectional shape, a line overlapping with a line formed by an end face on the thickness direction side of the laminate (A) is a line L, and the laminate L (A) side of the line L A curve M is an arcuate line that is located on the opposite side and forms the curved surface shape. Let O be any point on the curve M. Of the lines constituting the outer frame of the cross-sectional shape, S represents a line formed by the end surface on the thickness direction side of the quantum dot-containing layer, and S represents the end of the line S on the light transmissive substrate (i) side. _1, the end portion of the light transmissive substrate (ii) side of the line S and S _2. The length of a straight line connecting S ₁ and the arbitrary point O is S ₁ O, and the length of a straight line connecting S ₂ and the arbitrary point O is S ₂ O. The end of the line L on the light transmissive substrate (i) side is L ₁ , and the end of the line L on the light transmissive substrate (ii) side is L ₂ . When the _{L 1} and the _{S 1} and _L 1 _{S 1} the length of a straight line connecting, the length of a straight line connecting said _{L 2} and the _{S 2} was _L 2 _{S 2, S 1} O always L ₁ S ₁ or more, and S ₂ O always satisfies the relationship of L ₂ S ₂ or more.   The quantum dot sheet according to any one of claims 1 to 4, wherein the sealing portion (B) includes a light transmissive resin, and a refractive index of the light transmissive resin is 1.49 or more. The sealing part (B) includes a light-transmitting resin and particles, and includes any one or more particles selected from (a) to (c) below as the particles. The quantum dot sheet of item 1.
(A) Hollow particles (b) Metal particles or metal coating particles (c) When the refractive index of the light-transmitting resin is n ₁ and the refractive index of the particles is n ₂ , a relationship of 1.10 ≦ n ₂ / n ₁ Satisfy the particles.   The sealing part (B) includes one type or two or more types of phosphors, and the phosphor has a primary emission color of one type of phosphor or a combined color of emission of two or more types of phosphors. The quantum dot sheet according to any one of claims 1 to 6, which is a complementary color of a peak wavelength of light.   The quantum dot sheet according to claim 1, wherein the sealing part (B) is formed in substantially the entire region of the end face on the thickness direction side of the laminate (A).   A back provided with at least one light source that emits primary light, an optical plate that is disposed adjacent to the light source and that guides or diffuses light, and a quantum dot sheet that is disposed on the light exit side of the optical plate The backlight according to claim 1, wherein the quantum dot sheet is the quantum dot sheet according to claim 1.   A liquid crystal display device comprising a backlight and a liquid crystal panel, wherein the backlight is the backlight according to claim 9.