JP5835532B1 - Reflective film for edge light type backlight and backlight using the same - Google Patents

Abstract

An object of the present invention is to provide a reflective film for an edge light type backlight that is not easily damaged and a backlight using the same. The solution includes a material film and a particle-containing layer containing particles having a particle size of 25 to 50 μm and particles having a particle size of 1 to 15 μm,
It is to use the reflective film for an edge light type backlight having a convex portion satisfying the following requirements (i) to (iii) on at least one surface.
(I) There is a convex part having a diameter of 25 to 50 μm.
(Ii) The number of convex portions having a diameter of 25 to 50 μm is 10 to 100 per 0.64 mm ^2, which is present independently without contacting convex portions having a diameter of 25 to 50 μm.
(Iii) The number of convex portions included in the aggregate of convex portions with which the convex portions having a diameter of 25 to 50 μm continuously contact is 10 or less per 0.64 mm ² .

Description

  The present invention relates to a reflective film for a backlight and a backlight using the same.

  In the liquid crystal display, a backlight for illuminating the liquid crystal cell is used. Conventionally, depending on the type of liquid crystal display, an edge-light type backlight was adopted for a relatively small liquid crystal monitor, and a direct type backlight was adopted for a relatively large liquid crystal television. In recent years, with the thinning of liquid crystal televisions, the backlight of the edge light system has been adopted even in large liquid crystal televisions, and at the same time, the development of the backlight of the edge light system has been vigorously carried out. Furthermore, light-emitting diodes (hereinafter abbreviated as LEDs) are being adopted as light sources in order to reduce power consumption and mercury-free. As these reflective films for a backlight, a porous white film formed of bubbles is generally used (for example, Patent Document 1).

  An edge light type backlight uses a light guide plate as an optical member. As shown in FIG. 1, the light guide plate 2 and the reflective film 1 are generally arranged in contact with each other inside the backlight, and the reflective film 1 emits light irradiated to the reflective film side through the light guide plate 2. It has a function of reflecting and improving the luminance of the backlight. As for the light guide plate, a size up to about 25 inches is sufficient for conventional notebook computers and desktop monitors, but 30 to 60 inches are required for televisions. Therefore, acrylic resin, a mixture of acrylic resin and styrene resin, a plate made of styrene resin, glass, etc. is used as a substrate, dot printing is performed on it, or molding is performed using a mold or roll. Thus, a light guide plate 2 having a convex portion 5 as shown in FIG. 2 has been developed. Further, a light guide plate 2 having a concave portion as shown in FIG. 3 has been developed by performing laser processing on the substrate as shown above or molding it using a mold or a roll.

  In the development of the large and thin edge light type backlight as described above, the following problems occur due to the arrangement of the light guide plate and the reflective film in contact with each other, and it is a problem to improve this. It has become. That is, the problem is that the light guide plate and the reflective film are non-uniformly adhered to each other, causing optical unevenness in a planar shape, a line shape, or a dot shape (particularly, a portion that is brightly visible in a dotted shape is called white spot unevenness), When the reflective films rub against each other, there is a problem that the light guide plate is scratched and optical unevenness occurs, and it has been a problem to improve these. As a reflective film technique for improving these problems, a reflective film having a convex portion having a specific height has been proposed (Patent Document 2).

JP-A-8-262208 International Publication No. 2011/105294 Pamphlet

  In recent years, various changes have occurred in display design and backlight design due to further technological advances.

  In particular, an LED light bar is used in an edge light type backlight using an LED as a light source, but with respect to the position where the LED light bar is installed, it is conventionally arranged on the four sides of the display. For the purpose of reducing the cost by reducing the number of LED light bars and the number of LEDs, the arrangement has changed to two long sides, two short sides, one long side, and one short side.

  In addition, regarding the light guide plate, for the purpose of reducing the cost by reducing the resin amount of the light guide plate and the purpose of reducing the thickness of the display, a thickness of 3 mm or more is conventionally thinner than 3 mm, for example, 2 The thickness is reduced to 5 mm, 2 mm, 1 mm, and lower thicknesses.

  In addition, a plurality of optical films such as a diffusion film and a prism film have been used for the backlight until now, but the number of optical films is designed to be reduced in order to reduce the cost and to make the display thinner.

  From the design change described above, the performance required for the reflective film is higher.

  For example, when the temperature inside the backlight rises due to heat generated when the light source (for example, LED) is turned on, the light guide plate generally undergoes thermal deformation. In particular, in the edge light system, the temperature gradient inside the backlight tends to be larger at the portion close to and away from the LED light source due to the change in the position of the light source. Due to this temperature gradient, the degree of thermal expansion and contraction of the light guide plate is also different for each part. As a result, a dimensional difference is generated in the surface of the light guide plate, and the light guide plate is easily deformed like a wave. And the deformation | transformation of this light-guide plate becomes so remarkable that the thickness of a light-guide plate becomes small.

  At this time, the reflection film in contact with the light guide plate is fitted into the backlight in contact with the light guide plate with a substantially uniform load in the plane as long as the light guide plate maintains flatness. However, when the light guide plate is deformed, the light guide plate comes into contact with the light guide plate with a large load and is fitted into the backlight. At this time, at a position where the pressing load is large, the light guide plate and the reflective film rub against each other strongly, and the reflective film is likely to be damaged. Thus, when a dent-like scratch or streak-like scratch occurs on the surface of the reflective film itself, when light enters the reflective film from the light guide plate, a shadow is generated on the scratched portion of the reflective film, This shadow is visually recognized as optical unevenness on the screen.

  Such optical unevenness has been reduced by the use of optical sheets such as a plurality of diffusion films and prism films generally used for backlights. In recent backlight designs, it is difficult to reduce optical unevenness because the number of optical films is designed to reduce the cost of the backlight and reduce the thickness of the display.

  Therefore, there has been a demand for a reflective film that has improved the drawbacks of the dent-like scratches and streak-like scratches that occur in the reflective film itself, but the conventional reflective film has not been sufficiently improved.

  In view of the problems of the prior art, the present invention is intended to improve the quality defects of the reflective film, such as dents and streaks on the surface of the reflective film, in the reflective film for edge light type backlights. There is a need to provide a reflective film that can improve the optical unevenness of the backlight by reducing scratches.

The present invention employs any one of the following means in order to solve such a problem.
(1) having a particle-containing layer containing a base film and particles having a particle diameter of 25 to 50 μm and particles having a particle diameter of 1 to 15 μm;
An edge-light-type reflective film for a backlight, at least one of which satisfies the following requirements (i) to (iii):
(I) There is a convex part having a diameter of 25 to 50 μm.
(Ii) It exists independently without contacting convex portions having a diameter of 25 to 50 μm, and the number of convex portions having a diameter of 25 to 50 μm is 10 to 100 per 0.64 mm ² .
(Iii) The number of convex portions included in the aggregate of convex portions with which the convex portions having a diameter of 25 to 50 μm continuously contact is 10 or less per 0.64 mm ² .
(2) The reflective film for an edge light type backlight according to (1), wherein the surface satisfying the requirements of (i) to (iii) is the surface of the particle-containing layer.
(3) The edge-light-type reflective film for backlight according to (1) or (2), wherein SRz of the surface satisfying the requirements of (i) to (iii) is 15 to 60 μm.
(4) An edge light type backlight using the reflection film for an edge light type backlight according to any one of (1) to (3).

  According to the present invention, when at least one surface of the reflective film has a convex portion having specific characteristics, it is possible to improve the problem of the defects of the reflective film due to a dent or a streak on the surface of the reflective film. .

  Thereby, when the reflective film obtained by this invention is used for the edge-light-type backlight provided with the LED light source, and the surface light source for illumination, an optical nonuniformity can be decreased more.

It is a schematic diagram which shows one embodiment of the large sized edge light type backlight which used LED as the light source. It is a related schematic diagram of the light-guide plate which has a convex part, a reflective film, and a back housing | casing. It is a related schematic diagram of the light-guide plate which has a recessed part, a reflecting film, and a back housing | casing.

The present invention, as a result of intensive studies on the above-mentioned problem, that is, a reflection film that can improve the quality defects of the reflection film, such as dents and streaks on the reflection film surface, in the edge light type backlight, The invention has been devised to solve the above problem when a specific convex portion is provided on one side. Hereinafter, the reflective film according to the present invention will be described in detail. The reflective film of the present invention has a base film and a particle-containing layer.

<Basic structure of reflective film>
<< Base film >>
It does not specifically limit as a base film, Silver, the vapor deposition film of aluminum, the laminate film of silver foil or aluminum foil, a white film, a multilayer laminated film, etc. are mentioned. When the base film is used as a backlight for a liquid crystal display or a reflective film for illumination, it is preferable that the reflectance of visible light is high. For this reason, a film containing bubbles and / or incompatible particles inside can be used. As the film, a thermoplastic resin film is preferably used. These thermoplastic resin films include, but are not limited to, polyolefins and polyesters such as porous unstretched or biaxially stretched polypropylene films and porous unstretched or stretched polyethylene terephthalate films. A system film is preferably used. In particular, a polyester film is preferably used from the viewpoint of moldability and productivity.

  The methods for producing these thermoplastic resin films are disclosed in paragraphs [0034] to [0057] of JP-A No. 8-262208, paragraphs [0007] to [0018] of JP-A No. 2002-90515, and JP-A No. 2002-138150. It is disclosed in detail in paragraphs [0008] to [0034] of the publication.

  Among these, the porous biaxially stretched polyethylene terephthalate film disclosed in JP-A-2002-90515 can be preferably used as the base film in the present invention for the reasons described above. Furthermore, a porous white biaxially stretched polyethylene terephthalate film obtained from a mixture of polyethylene terephthalate and polyethylene naphthalate or a copolymer thereof is preferable from the viewpoint of heat resistance and reflectance. In particular, a porous biaxially stretched polyethylene terephthalate film containing inorganic particles is preferable in order to improve the flame retardancy of the thermoplastic resin film itself. The inorganic particles are preferably 2% by mass or more with respect to the total mass of the thermoplastic resin film, more preferably 7% by mass or more, still more preferably 10% by mass or more, and most preferably 30% by mass or more.

  The structure of the base film according to the present invention may be appropriately selected depending on the intended use and required characteristics, and is not particularly limited. Specifically, a single layer having a configuration of at least one layer and a composite film of two or more layers can be exemplified, and it is preferable that at least one or more layers contain bubbles and / or inorganic particles.

  A film having a single layer structure is a film composed of only a single layer. This layer contains inorganic particles and / or bubbles.

  The film having a two-layer structure is a film having a structure of A layer / B layer obtained by laminating an A layer and a B layer. In at least one of these A layer and B layer, inorganic particles and / or Or air bubbles are contained. The content of the inorganic particles is preferably 2% by mass or more, more preferably 7% by mass or more, and further preferably 10% by mass or more with respect to the total mass of the base film, that is, the total mass of the two layers. Most preferably, it is 30% by mass or more.

  Furthermore, a film having a three-layer structure is a film having a structure of A layer / B layer / A layer or A layer / B layer / C layer, and inorganic particles and / or bubbles in at least one of these layers. Containing. Similar to the two-layer film, the inorganic particles are preferably 2% by mass or more, more preferably 7% by mass or more, still more preferably 10% by mass or more, most preferably based on the total mass of the base film. Is 30% by mass or more. In the case of a three-layer configuration, the B layer most preferably contains bubbles from the viewpoint of productivity.

  The number average particle diameter of the inorganic fine particles contained in the base film is preferably 0.3 to 2.0 μm.

  Examples of the inorganic particles include calcium carbonate, magnesium carbonate, zinc carbonate, titanium oxide, zinc oxide, cerium oxide, magnesium oxide, barium sulfate, zinc sulfide, calcium phosphate, silica, alumina, mica, titanium mica, talc, clay, Kaolin, lithium fluoride, calcium fluoride, or the like can be used.

  Next, the manufacturing method of the thermoplastic resin film of 3 layer structure among the said base film is demonstrated. However, the present invention is not limited to this example.

First, polymethylpentene is added as an incompatible polymer, and a copolymer of polyethylene glycol, polybutylene terephthalate, and polytetramethylene glycol is added as a low specific gravity agent to polyethylene terephthalate. The mixture is sufficiently mixed and dried, and then supplied to the extruder B heated to a temperature of 270 to 300 ° C. Polyethylene terephthalate containing inorganic and / or organic additives such as BaSO ₄ , CaCO ₃ and TiO ₂ is supplied to the extruder A by a conventional method. Then, in the T-die three-layer die, the polymer of the extruder B is arranged on the inner layer (B layer) and the polymer of the extruder A is arranged on both surface layers (A layer), so that A layer / B layer / A They are stacked in three layers with a layer structure.

  The preferable manufacturing method of a base film is demonstrated below. The sheet in which the polymer is melted is closely cooled and solidified by electrostatic force on a drum having a drum surface temperature of 10 to 60 ° C. to obtain an unstretched film. The unstretched film is guided to a roll group heated to 80 to 120 ° C., longitudinally stretched 2.0 to 5.0 times in the longitudinal direction, and cooled with a roll group of 20 to 50 ° C. Subsequently, the film is stretched in the direction perpendicular to the longitudinal direction in an atmosphere heated to 90 to 140 ° C. while being guided to a tenter while gripping both ends of the longitudinally stretched film with clips. In this case, the stretching ratio is preferably 2.5 to 4.5 times in the longitudinal and lateral directions, but the area ratio (longitudinal stretching ratio x lateral stretching ratio) is preferably 9 to 16 times. That is, when the area magnification is small, the amount of air bubbles and the amount of holes in the obtained film may not be sufficient. On the other hand, if the area magnification is too large, the film tends to be broken at the time of stretching, and the film forming property may be lowered. In order to impart flatness and dimensional stability to the biaxially stretched film in this manner, heat setting is performed at 150 to 230 ° C. in a tenter, uniformly cooled, and further cooled to room temperature. To obtain a substrate thermoplastic resin film. Note that the thickness of the base film is, for example, preferably in the range of 30 μm or more, preferably 100 or more, and 1,000 μm or less.

<< particle-containing layer >>
The reflective film of the present invention has a particle-containing layer. The particle-containing layer is preferably present adjacent to the base film. Although it does not specifically limit as a formation method of a particle content layer, The following method is mentioned.
(I) A method in which a resin layer containing particles is bonded to at least one surface of a base film, or a coating liquid containing particles is applied and dried.
(II) A method of laminating a particle-containing layer by extruding together a resin raw material containing particles when producing a base film by melt extrusion.

  The preferred thickness of the particle-containing layer is 0. 1 μm or more and 500 μm or less. It is preferable for the thickness to be 0.1 μm or more, since it becomes difficult to have a dent-like scratch or streak-like scratch on the surface of the reflective film. When the thickness is 500 μm or less, the particle-containing layer can be favorably formed on the surface of the base film, and the reflective film is less likely to cause curling and the like, and the flatness is improved.

<< Convex part on the surface of the reflective film >>
The reflective film of the present invention has a convex portion on at least one surface. The convex portion can be generated by particles contained in the particle-containing layer. Here, what a plurality of convex portions are in contact with each other is referred to as an aggregate of convex portions. In counting the number of convex portions, the aggregate is not counted as one convex portion, but the number of convex portions in the aggregate of interest.

  When any surface of the reflection film has a convex portion, the effect of preventing scratches such as dents and streaks on the surface of the reflection film, and further preventing unevenness caused by the reflection film sticking to the light guide plate is exhibited. The presence and size of the convex portion can be confirmed by observing the surface of the reflective film with an electron microscope.

The reflective film of this invention has the convex part which satisfy | fills all the following requirements on an at least one surface. Hereinafter, this surface is referred to as a “characteristic surface”.
(I) There is a convex part having a diameter of 25 to 50 μm.
(Ii) The number of protrusions having a diameter of 25 to 50 μm that do not contact the protrusions having a diameter of 25 to 50 μm and that exist independently is 10 to 100 per 0.64 mm ² .
(Iii) The number of convex portions included in the aggregate of convex portions with which the convex portions having a diameter of 25 to 50 μm continuously contact is 10 or less per 0.64 mm ² .

  The characteristic surface is preferably the surface of the particle-containing layer. The characteristic surface has convex portions having a diameter of 25 to 50 μm. This is preferable because it can prevent scratches such as dents and streaks on the surface of the reflective film and prevent light unevenness caused by the reflective film sticking to the light guide plate.

  Moreover, it is preferable that the convex part with a diameter of 25-50 micrometers exists independently without contacting as much as another convex part with a diameter of 25-50 micrometers in the characteristic surface. Here, “a convex part having a diameter of 25 to 50 μm exists independently without contacting another convex part having a diameter of 25 to 50 μm” when observed with an electron microscope by the method described later. It means that one convex portion having a diameter of 25 to 50 μm is not in contact with another convex portion having a diameter of 25 to 50 μm. Here, “contact” refers to a case where the shortest distance from the outermost part of a convex part to the outermost part of another convex part is 0.005 μm or less when two convex parts are observed by a method described later. . That is, when the shortest distance from the outermost part of a convex part to the outermost part of another convex part is larger than 0.005 micrometer, it is assumed that it is not contacting.

The number of protrusions having a diameter of 25 to 50 μm that does not contact other protrusions having a diameter of 25 to 50 μm and exists independently is 10 to 100 at 0.64 mm ² . The lower limit is preferably 15 or more, more preferably 20 or more. The upper limit is preferably 75 or less, more preferably 50 or less. When the number of convex portions having a diameter of 25 to 50 μm, which does not contact other convex portions with a diameter of 25 to 50 μm and is independently present, is out of the above range, the effect of preventing the depression of the reflective film surface, streaks, etc. The effect of preventing scratches may not be exhibited.

  In the present invention, there may be a case where an aggregate of convex portions in which convex portions having a diameter of 25 to 50 μm continuously contact is formed. Here, “an assembly of convex portions that are in contact with each other” means that two or more convex portions are in contact with each other. Whether or not “contacting” is determined is determined by the same method as described above.

In such an aggregate of convex portions where the convex portions having a diameter of 25 to 50 μm continuously contact , when the range of 0.64 mm ² is observed , the number of convex portions included in the aggregate of convex portions is 0. The number is preferably 10 or less per 64 mm ² . Here, “the number of protrusions having a diameter of 25 to 50 μm that are in continuous contact is 10 or less” means that a plurality of protrusions are in continuous contact to form an aggregate of protrusions. The average number of convex portions constituting one aggregate is 10 or less.

In the assembly of convex portions, when the number of convex portions is 10 or less per 0.64 mm ^{2, the} occurrence of streak-like defects is suppressed in the step of forming the particle-containing layer.

  SRz in the measurement of the surface roughness of the characteristic surface is preferably 15 to 60 μm. The lower limit of SRz is preferably 15 μm or more, more preferably 20 μm or more, and further preferably 25 μm or more. The upper limit of SRz is preferably 60 μm or less, more preferably 50 μm or less, and still more preferably 45 μm or less. If SRz is too small, scratches such as dents and streaks on the surface of the reflective film may be reduced, and the effect of preventing unevenness caused by the reflective film sticking to the light guide plate may be reduced. If SRz is too large, scratches such as dents and streaks on the surface of the reflective film may be noticeable. When the particle diameter of the particles forming the convex portion is increased, SRz becomes too large, and a streak-like defect is generated on the surface of the reflective film in the step of forming the particle-containing layer, or the particles fall off after forming the particle-containing layer. As a result, a depression may occur on the surface of the reflective film.

  A method for forming a convex portion having a characteristic surface is not particularly limited, and examples thereof include the following methods.

  When producing a particle-containing layer by the method (I) above, an appropriate binder resin and particles are mixed in an appropriate solvent (such as an organic solvent), and the resulting mixture is applied to a substrate film and then dried. By this, the method of forming a granular convex part in a particle content layer.

  In the case of producing a particle-containing layer by the production method (II) above, in the step of producing a film by melt extrusion, the particles are kneaded in advance in the resin that forms the particle-containing layer, and the resin that forms the base film There is a method of extruding together and forming convex portions in the particle-containing layer in the stretching step.

  Among these, the method of apply | coating a mixture to a base film is preferable at the point which can achieve high performance economically.

<< Particles in particle-containing layer >>
The material of the particles is not particularly limited, and any organic or inorganic material can be used. As for the shape, either spherical particles or particles having other shapes can be selected. Spherical particles are preferred to give the features of the convex portions of the present invention. Examples of organic particles include acrylic resin particles, silicone resin particles, nylon resin particles, styrene resin particles, polyethylene resin particles, polypropylene resin particles, benzoguanamine resin particles, urethane resin particles, and polyester resin particles. Etc. can be used. As the inorganic particles, silica, aluminum hydroxide, aluminum oxide, zinc oxide, barium sulfide, magnesium silicate, and a mixture thereof can be used.

  When the particle-containing layer is provided by coating, the coating solution usually contains a binder resin. When using an acrylic monomer, which will be described later, or a binder resin made of a copolymer of an acrylic monomer and an ultraviolet absorber, the acrylic resin is used due to the relationship between the refractive index difference between the binder resin and the particles, particle dispersibility, coatability, etc. It is preferable to use resin-based resin particles, polyethylene-based resin particles, silicone-based resin particles, nylon-based resin particles, urethane-based resin particles, and polyester-based resin particles. Furthermore, polyethylene-based resin particles and nylon-based resin particles are more preferable because of scratch resistance to the light guide plate. Further, nylon-based resin particles are preferable in terms of white spot unevenness, and most preferable are nylon 12 resin particles and / or resin particles made of nylon 6 and nylon 12 copolymers. On the other hand, polyethylene-based resin particles are preferred as the particles that are less likely to cause streak-like defects that occur in the step of forming the particle-containing layer. Of these particles, two or more types of particles having different particle materials may be used in combination.

  In the present invention, the particle-containing layer contains particles having a particle diameter of 25 to 50 μm and particles having a particle diameter of 1 to 15 μm. By containing particles having a particle diameter of 25 to 50 μm in the particle-containing layer, convex portions having a diameter of 25 to 50 μm can be suitably formed, which is preferable.

  Further, by containing particles having a particle diameter of 1 to 15 μm, convex portions with a diameter of 25 to 50 μm exist independently without contacting with other convex portions with a diameter of 25 to 50 μm and exist independently. It becomes easy to make the number of the convex parts made into the range of the present invention. That is, when a particle having a particle diameter of 1 to 15 μm is contained, a convex part having a diameter of 25 to 50 μm has an increased chance to come into contact with a convex part formed by particles having a particle diameter of 1 to 15 μm. It becomes difficult to contact other convex portions of 25 to 50 μm. In order to effectively develop the effect that the convex portion having a diameter of 25 to 50 μm is less likely to come into contact with another convex portion having a diameter of 25 to 50 μm, it is preferable to contain particles having a particle diameter of 1 to 5 μm. More preferably, it contains particles of 1 to 3 μm.

  Here, the particle diameter of the particles is determined by observing the particles and drawing a square or rectangle having the smallest area in contact with the four sides. In the case of a square, the length of one side, and in the case of a rectangle, the length of the long side Adopted.

  In the particle-containing layer of the present invention, it is preferable to use a combination of two or more particles having different particle diameters. By using a combination of two or more kinds of particles having different particle diameters, a particle-containing layer containing particles having a particle diameter of 25 to 50 μm and particles having a particle diameter of 1 to 15 μm can be effectively formed.

  Although the addition amount of particle | grains is not specifically limited, It is preferable that it is 17 mass% or more with respect to the whole particle-containing layer, More preferably, it is 19 mass% or more. On the other hand, 90 mass% or less is preferable, More preferably, it is 60 mass% or less, More preferably, it is 56 mass% or less. The addition amount of these particles is the total amount of all two or more types of particles when two or more types of particles are used in combination. When the amount added is too small or too large, the effect of preventing scratches such as dents and stripes on the surface of the reflective film may be reduced. In addition, when the addition amount is too large, streak-like defects are generated in the step of forming the particle-containing layer, which may already be a problem before the use of the reflective film.

  Moreover, it is preferable that the addition amount of a particle | grain with a particle diameter of 25-50 micrometers or more is 7 mass% or more and 55 mass% or less with respect to the whole particle-containing layer. More preferably, it is 9 mass% or more, More preferably, it is 12 mass% or more. More preferably, it is 40 mass% or less. Moreover, it is preferable that the addition amount of a particle | grain with a particle diameter of 1-15 micrometers is 10 to 35 mass% with respect to the whole particle-containing layer. The upper limit is more preferably 24% by mass or less, and still more preferably 16% by mass or less.

  A preferable mass ratio (mass of the former particles / mass of the latter particles) of the particles having a particle diameter of 25 to 50 μm and the particles having a particle diameter of 1 to 15 μm is 0.61 or more and 6.49 or less. More preferably, it is 0.63 or more and 5.5 or less, More preferably, it is 0.63 or more and 2.5 or less, More preferably, it is 0.75 or more and 2.5 or less.

<< Resin other than particles in particle-containing layer >>
When the particle-containing layer is provided on at least one surface of the base film by applying a coating liquid, the binder resin is not particularly limited. For example, polyester resin, polyurethane resin, acrylic resin, methacrylic resin, polyamide resin, polyethylene resin , Polypropylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, fluorine resin, silicone resin and the like. These resins are suitably used as resins other than particles even when the particle-containing layer is provided by a method other than coating. Moreover, these resins may be used alone or in combination of two or more. Of these, polyester resins, polyurethane resins, acrylic resins and methacrylic resins are preferably used from the viewpoints of heat resistance, particle dispersibility, coating liquid coating properties, and glossiness of the resulting reflective film.

  In terms of light resistance of the particle-containing layer, it is preferable that the particle-containing layer contains an ultraviolet absorber and a light stabilizer. As the ultraviolet absorber and the light stabilizer, there are an inorganic type and an organic type. It does not specifically limit regarding the form contained, You may mix resin which forms this particle | grain containing layer, and an ultraviolet absorber or a light stabilizer. On the other hand, when it is desired to prevent the ultraviolet absorber or the light stabilizer from bleeding out from the particle-containing layer, it may be copolymerized with a resin monomer contained in the particle-containing layer. Moreover, you may make it chemically bond with the resin contained.

  As the inorganic ultraviolet absorber, titanium oxide, zinc oxide and cerium oxide are generally known, and at least one selected from the group consisting of zinc oxide, titanium oxide and cerium oxide does not bleed out. It is preferably used from the viewpoints of economy, light resistance, ultraviolet absorption, and photocatalytic activity. Such ultraviolet absorbers may be used in combination of several kinds as required. Of these, zinc oxide or titanium oxide is most preferable from the viewpoints of economy, ultraviolet absorption, and photocatalytic activity.

  Examples of organic ultraviolet absorbers include benzotriazole and benzophenone. In particular, benzotriazole can be suitably used because it contains nitrogen in the structure and thus has a function as a flame retardant, but is not particularly limited thereto. Since these ultraviolet absorbers only absorb ultraviolet rays and cannot capture organic radicals generated by ultraviolet irradiation, the radicals may cause the thermoplastic resin film of the base material to deteriorate in a chain manner. In order to capture these radicals and the like, a light stabilizer is preferably used in combination, and a hindered amine compound (HALS) is preferably used as the light stabilizer.

  When the ultraviolet absorber has a particle shape regardless of whether it is inorganic or organic, it can be used as a particle having a particle diameter of 25 to 50 μm or a particle having a particle diameter of 1 to 15 μm.

  Here, as a monomer that can be copolymerized to fix such an organic ultraviolet absorber or light stabilizer, vinyl monomers such as acrylic and styrene are highly versatile and economically preferable. Among these monomers, styrene-based vinyl monomers have an aromatic ring and therefore tend to yellow. In terms of light resistance, copolymerization with acrylic monomers is most preferably used.

  Moreover, 2- (2'-hydroxy-5'-methacryloxyethylphenyl) -2H-benzotriazole (trade name: RUVA-93); Otsuka Chemical Co., Ltd. ))) Can be used. Further, as a combination of a hindered amine compound and a reactive vinyl monomer, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine (““ ADEKA STAB ”(registered trademark) LA-82”; ADEKA Corporation) Can be used.

  In the present invention, examples of such organic ultraviolet absorbers include resins containing organic ultraviolet absorbers such as benzotriazole and benzophenone, resins obtained by copolymerizing benzotriazole and benzophenone monomers, and hindered amines ( Resins containing and / or copolymerizing light stabilizers such as HALS-based reactive monomers can be used.

  Organic UV-absorbing resins containing a resin obtained by copolymerizing such benzotriazole-based and benzophenone-based reactive monomers, and further a resin copolymerized with a hindered amine (HALS) -based reactive monomer are more preferable because of their high UV absorbing effect. Of these, benzotriazole is particularly preferable because it contains nitrogen in the structure and also has a function as a flame retardant.

  These production methods and the like are disclosed in detail in paragraphs [0019] to [0039] of JP-A-2002-90515. In addition, “Hals Hybrid” (registered trademark) (manufactured by Nippon Shokubai Co., Ltd.) containing an acrylic monomer and ultraviolet absorber copolymer as an active ingredient can be used.

<< Formation method of particle-containing layer by coating >>
In forming the particle-containing layer on at least one surface of the base film by coating, any method can be employed. For example, a coating solution containing a binder resin and particles in a solvent is a gravure coat, roll coat, spin coat, reverse coat, reverse kiss coat, bar coat, screen coat, blade coat, air knife coat, slit die coat, lip Examples of the method include applying at the time of manufacturing a base film using a variety of coating methods such as coating and dipping, and applying on the base film after completion of crystal orientation. The former application method is called in-line coating, and the latter application method is called off-line coating. When there is little restriction on the effective coating width and it is desired to flexibly respond to changes in product width, reverse kiss coating can be most preferably used.

  The solvent that can be used for mixing the binder resin and the particles constituting the particle-containing layer is a liquid having a property of dissolving the binder resin. After the coating liquid is applied to the substrate film surface, the solvent is vaporized. Solvents include aromatic hydrocarbons such as toluene, xylene and styrene, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, alcohols such as methanol, isopropyl alcohol and isobutyl alcohol, chlorobenzene, and orthodichlorobenzene. Chlorinated aromatic hydrocarbons such as monochloromethane and monochloroethane, esters such as methyl acetate, ethyl acetate and butyl acetate, ethers such as ethyl ether and 1,4-dioxane, ethylene Examples include glycol ethers such as glycol monomethyl ether, alicyclic hydrocarbons such as cyclohexane, and aliphatic hydrocarbons such as normal hexane. Of these, aromatic hydrocarbon-based, ketone-based and ester-based organic solvents are preferable.

  The binder resin is not particularly limited as long as it dissolves, but methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, and butyl acetate are preferable in terms of solubility, versatility, and cost. In addition, it is preferable to use a mixture of two or more solvents having different boiling points in that the drying speed can be adjusted.

<< Other additives that can be used in the base film and particle-containing layer >>
Such a base film and a particle-containing layer can contain various additives. Examples of such additives include fluorescent brighteners, crosslinking agents, heat stabilizers, oxidation stabilizers, organic lubricants, antistatic agents, nucleating agents, dyes, pigments, fillers, dispersants, flame retardants and cups. There are ring agents.

<Application of reflective film>
The reflective film of the present invention is used for an edge light type backlight, and among them, it can be suitably used for an edge light type liquid crystal display backlight and an illumination surface light source such as a signboard or a vending machine.

  In addition, it can be suitably used as a reflection film constituting various surface light sources, a sealing film for solar cell modules that require reflection characteristics, and a back sheet. In addition, paper substitutes, ie cards, labels, stickers, home delivery slips, video printer paper, inkjet, barcode printer paper, posters, maps, dust-free paper, display boards, white boards, thermal transfer, offset printing, telephones Receiving sheet base materials used for various printing records such as cards and IC cards, building materials such as wallpaper, lighting equipment and indirect lighting equipment used indoors and outdoors, members mounted on automobiles, railways, aircraft, etc., circuit materials, etc. It can also be used as an electronic component.

<Edge light type backlight>
<< Configuration of edge light type backlight >>
The reflective film of this invention is used suitably for an edge light type backlight. In the edge light type backlight, for example, the reflective film of the present invention and the light guide plate are incorporated in this order in a casing, and the reflective film is incorporated so that the particle-containing layer side faces the light guide plate. A light source such as an LED is installed at the edge portion of the light guide plate. Furthermore, an optical film such as a diffusion film or a prism film may be installed on the front surface of the light guide plate (the side opposite to the reflection film).

  By using the reflective film of the present invention for such an edge light type backlight, a good quality backlight without optical unevenness can be obtained.

  The size (rectangular diagonal length) of the backlight for a liquid crystal display using an LED as a light source that exhibits the effects of the present invention more effectively is 76.2 cm (30 inches) or more, preferably 88.9 cm. (35 inches) or more, more preferably 101.6 cm (40 inches) or more, and most preferably 127 cm (50 inches) or more.

  Moreover, it is preferable that the light guide plate is provided with a recess or projection of 3 μm or more on the surface of the light guide plate in the edge light type backlight. Furthermore, it is preferable that a concave or convex portion of 10 μm or more is provided.

The irregularities on the surface of the light guide plate are defined as follows.
(I) Take out the light guide plate arranged above the reflective film from the liquid crystal television.
(Ii) The light guide plate is cut into a 5 cm square, and any five sheets are taken out.
(Iii) Using a laser microscope VK-9700 manufactured by Keyence Co., Ltd., observation is performed with the magnification of the objective lens set to 20 times, and a portion detected at a height or depth of 1 μm or more is defined as surface irregularities.

  As the material of the light guide plate, an acrylic resin, a resin in which an acrylic resin and a styrene resin are mixed, a styrene resin, glass, or the like is used.

  The light guide plate 2 having the convex portions as shown in FIG. 2 subjected to dot printing is preferable in terms of production capacity. In addition, a light guide plate having a concave portion formed by laser processing or a light guide plate having a convex portion or a concave portion formed by molding using a mold or a roll is less likely to cause loss of light absorption or the like at the dot printing portion. Therefore, it is preferable in terms of high backlight luminance.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples. First, measurement methods and evaluation methods are shown below.

(1) Material of particles contained in particle-containing layer Using a stereo microscope (Nikon, SMZ1500), adjust the overall magnification appropriately at 20 to 200 times, and observe the surface of the particle-containing layer with a metal jig The particles contained in the convex portions were sampled and used as a measurement target sample.

The obtained sample was further cut, and the vicinity of the center of the particles was measured by a microscopic FT-IR method.
The above-described particle sampling, cutting treatment, and measurement by the microscopic FT-IR method were performed at two locations for convex portions of 25 μm or more and at two locations for convex portions of 15 μm or less.

  Next, the material of the particles contained in the convex portion was determined from the infrared light absorption waveform of the microscopic FT-IR obtained as described above.

The device names and measurement conditions used in the microscopic FT-IR method are shown below.
Apparatus: Microscopic infrared spectroscopic analyzer IR μs (manufactured by SPECTRA-TECH)
conditions:
Light source Silicon carbide rod heating element (Glover)
Detector Narrow MCT (HgCdTe)
Detection wave number range 4000-650 cm ⁻¹
Purge Nitrogen gas measurement mode Transmission method Resolution 8cm ^-1
Number of integrations 512 times Data correction: Baseline correction.

(2) Mass of particle | grain containing layer The reflective film was cut out to length 100mm x width 100mm, and mass was measured. This value was defined as mass 1. Next, with the particle-containing layer on the top surface, the reflective film is placed on a mass balance (manufactured by Yamato, product number SD-12, use range 500 g to 12 kg, scale 50 g, type approval No. D9812, accuracy class 0). Placed on top. At this time, the double-sided tape was stuck on the back surface of the four corners of the reflective film, and the pan of the mass scale and the reflective film were fixed. Next, a non-woven fabric impregnated with methyl ethyl ketone (“Hize Gauze”, NT-4, 25 cm × 25 cm, 4 folds, distributor: Kawamoto Sangyo Co., Ltd.) is folded in two, and a square columnar metal bar with a bottom of 10 mm × 10 mm It was tied to a metal rod with a rubber band so as to cover the bottom of one side of the. Next, rub the particle-containing layer of the reflective film fixed on the pan of the mass scale with a load that makes the scale scale 1.5 to 2.5 kg on the surface of the metal rod to which the nonwoven fabric is bound. It was. At the time of rubbing, rubbing is performed 10 reciprocations in each of a range of 100 mm in length × 10 mm in width, and this operation is repeated 10 times while shifting horizontally to rub the entire surface of the particle-containing layer of 100 mm in length × 100 mm in width. Next, the double-sided tape was peeled off, the reflective film was removed from the pan of the weight scale, and allowed to stand at room temperature to evaporate methyl ethyl ketone, and then the mass was measured. This value was mass 2. The mass of the particle-containing layer was determined by calculating (mass 1-mass 2).

(3) Particle content ratio in particle-containing layer About 10 mg of the particle-containing layer was scraped off, and the mass was accurately measured. This mass is mass 3. Next, 25 ml of MEK was measured and put into a cylindrical glass bottle with a lid with a capacity of 50 ml and a diameter of 35 mm together with the shaved particle-containing layer. Next, the stirring bar was put in the glass bottle and stirred for 24 hours, and then the stirring bar was taken out. Next, filter paper (MILLIPORE, “OMNIPORE”, CAT NO. JGWP02500) was cut into a circle having a diameter of 21 mm, and the mass was measured. This value is mass 4. After measuring the filter, place the filter paper on a funnel (SB-21, 21φ, manufactured by Kiriyama Seisakusho Co., Ltd.), set the funnel in a suction bottle for vacuum filtration, put the liquid in the glass bottle into the funnel, and perform vacuum filtration It was. The filter paper after the filtration operation is placed on a hot plate set at 90 ° C. to dry methyl ethyl ketone, and then the mass of the filter paper after the filtration operation is measured. This value is mass 5. The ratio of the amount of particles in the particle-containing layer was calculated by the following formula.

  Particle amount ratio in particle-containing layer = (mass 5−mass 4) ÷ mass 3.

(4) SRz
SRz on the surface of the reflective film was measured under the following conditions using a micro shape measuring machine Surfcorder ET4000A manufactured by Kosaka Laboratory. Measurements were made at three randomly selected locations, and the average value was taken as SRz.
Measuring terminal: Diamond, tip R = 2μm
Measuring force: 100μN
Measurement length: 1mm
Measurement speed: 0.1 mm / sec. Cutoff setting: R + W.

(5) Presence of particles having a particle diameter of 25 to 50 μm and particles having a particle diameter of 1 to 15 μm The reflective film was cut at a randomly selected position, and a scanning electron microscope (S-3400N, manufactured by Hitachi, Ltd.) First, the cross section was observed at a magnification of 1,000 times. A square or rectangle having the smallest area in contact with the particles on the four sides was drawn. The length of one side was adopted for the square, and the length of the long side was adopted for the rectangle. By this method, the particle diameter of each of 500 randomly selected particles was measured.

  In addition, when 500 particles were not observed in one image, the image of another cut | disconnected cross section was further image | photographed in the different position of a reflective sheet, and the particle diameter of a total of 500 particles was measured. Of the 500 particles, if there are one or more particles in each particle size range, it is assumed that there are particles in each particle size range. In Table 2, “present” is indicated when particles are present, and “absence” is indicated when particles are not present.

(6) Number of convex portions having a diameter of 25 to 50 μm that do not contact the convex portions having a diameter of 25 to 50 μm and exist independently The scanning electron microscope (S-3400N, manufactured by Hitachi, Ltd.) First, the contour of the convex portion was observed at a magnification of 100 times and an acceleration voltage of 7.50 kV. The field of view of the image at a magnification of 100 was 1.27 mm × 0.885 mm. The center 0.8 mm × 0.8 mm of this image was selected, and the number of convex portions having a diameter of 25 to 50 μm that exist independently without contacting the convex portions having a diameter of 25 to 50 μm was counted. Here, the diameter of the convex portion is drawn from the contour of the convex portion of the SEM image by drawing a square or rectangle having the smallest inscribed area on the four sides, the length of one side in the case of a square, The length of the long side was adopted as the diameter of the convex part.

Whether or not the convex portion is “contacting” was determined by the following operation.
The image was printed out on paper so that 50 μm in an image taken at a magnification of 100 times became 10 mm. The printed out paper was observed with a universal projector (model number: V-16A, manufactured by Nikon Corporation, observation limit: 0.001 mm). At this time, 0.001 mm in the universal projector corresponds to 0.005 μm in an image photographed at 100 times. The shortest distance from the outermost part of the particle to the outermost part of the other convex part is measured for all the convex parts included in the image, and is 0.001 mm or less on the printed paper (that is, 0.000 for an image photographed at 100 times magnification). If it is equal to or less than 005 μm), it was determined that the convex portion was in “contact”. Further, the shortest distance from the outermost part of the convex part to the outermost part of the other convex part is measured, and is larger than 0.001 mm on the printed paper (that is, a distance larger than 0.005 μm in an image photographed at 100 times). In this case, it was determined that the convex portion was not “contacting”.

  The surface of the reflective film was measured at five different locations, and the average of the five locations was defined as the number of convex portions having a diameter of 25 to 50 μm that exist independently without contacting the convex portions having a diameter of 25 to 50 μm. The average value is rounded off to the nearest whole number.

  Here, the diameter of the convex portion is a square or rectangle in which the convex portion is inscribed on the four sides and has the smallest area, and the length of one side is adopted for the square, and the length of the long side is adopted for the rectangular shape. .

(7) Number of convex portions included in the convex portion assembly in which convex portions having a diameter of 25 to 50 μm continuously contact the surface of the reflective film with a scanning electron microscope (S-3400N, manufactured by Hitachi, Ltd.). First, it was observed at a magnification of 100 times. The field of view of the image at a magnification of 100 was 1.27 mm × 0.885 mm. The center 0.8 mm × 0.8 mm of this image was selected, and the number of convex portions included in the aggregate of convex portions in which convex portions having a diameter of 25 to 50 μm were in continuous contact was counted. When a plurality of aggregates were found in the obtained image, the number of convex portions included in each aggregate was counted for all aggregates. In addition, the judgment whether it was contacting was performed by the method similar to the method mentioned above.

  Measurement was performed on 10 aggregates having convex portions having a diameter of 25 to 50 μm, and the average number of convex portions in contact with each other was obtained. In Table 2, “10 or less” is described when the average value of the number of convex portions is 10 or less, and “10 or more” is described when 10 or more is exceeded.

(8) Dispersibility Evaluation of Particles 25 ml of the coating liquid prepared in Examples and Comparative Examples was weighed and placed in a 50 ml glass bottle with a lid (35 mm diameter cylindrical shape), and allowed to stand for 24 hours with the lid on. did. The coating solution contained in the glass bottle after 24 hours was visually observed, and the following determination was made.
Class AA: No separation is observed in the liquid layer or separation is observed in the liquid phase (separation into a phase with few particles and a phase with many particles), but the height of the phase with few particles is the height of the entire liquid. It was less than 1 / min.
Class A: Separation was observed in the liquid phase (separated into a phase with few particles and a phase with many particles), and the height of the phase with few particles was larger than 1/3 of the total height of the liquid and not more than 4/5 there were.
Class B: Separation was observed in the liquid phase (separated into a phase with few particles and a phase with many particles), and the height of the phase with few particles was larger than 4/5 of the total height of the liquid.

(9) Scratch on the reflective film Magnet on one side of acrylic plate 50 mm long × 50 mm wide and 3 mm thick (Seller: MITSUYA CORPORATION, “BISIX” (registered trademark) color magnet, round, φ20 mm product, product number: BX4 Three pieces of 13-YL (yellow) were pasted. The pasting position was a position where the magnets were in contact with each other, the line connecting the centers of the magnets was an equilateral triangle, and the center of the equilateral triangle was the center of the acrylic plate. A double-sided tape was used for pasting. The magnet was placed so that the magnet surface of the magnet was on the acrylic plate side and the resin surface of the magnet was in the opposite direction to the acrylic plate.

  Next, a 32-inch liquid crystal display (manufactured by Hisense Japan Co., Ltd., 32 type liquid crystal TV (model number: LHD32K15JP)) is disassembled, and an edge light type backlight using an LED as a light source (hereinafter referred to as “backlight A”). Was taken out. Further, a light guide plate (acrylic plate, 4 mm thickness) provided with a convex shape on one side was taken out and cut into 50 mm × 100 mm.

  Next, the reflective film cut out to 50 mm x 100 mm was piled up on the surface side where the convex part of the light guide plate was provided so that the surface on which the particle-containing layer was laminated was in contact.

  Subsequently, the acrylic plate on which the magnet was attached was overlaid from above the reflective film so that the two corners of the acrylic plate overlapped with the two corners of the reflective film and the light guide plate, respectively. When stacking, the resin surface of the magnet was in contact with the reflective film.

  Furthermore, a weight was placed on the acrylic plate on the side where the magnet was not attached. Two weights were used: a case where four 100 g weights each having a diameter of 34 mm and a thickness of 13 mm were placed on top of each other, and a case of placing a 750 g weight having a diameter of 48 mm and a thickness of 45 mm.

  Next, the end of the reflective film on which the acrylic plate was not overlapped was held by hand and pulled 50 mm in the direction opposite to the acrylic plate in the direction perpendicular to the thickness direction of the reflective film over 3 seconds. At this time, the acrylic plate on which the reflective film and the magnet were attached moved together on the light guide plate.

After performing the above operation, the reflective film is taken out, and a three-wavelength fluorescent lamp (Toshiba Lighting & Technology Co., Ltd., FHF32EX-N-H, Hf “Mellow Line” (registered trademark in Japanese characters)) fluorescent lamp, three-wavelength daylight A reflective film was placed on the desk in the room that was lit white. At this time, the reflective film was placed directly under the fluorescent lamp so that the particle-containing layer was opposite to the desk, and scratches on the reflective film were observed. The observation was performed such that the angle formed by the straight line drawn from the reflective film surface and the portion of the reflective film on which the acrylic plate was placed toward the eyes was 45 degrees. According to the following criteria, it was judged as Class A, B, C, and D.
Class A: Scratches are not visible at 400g or 750g weight Class B: Scratches are not visible at 400g weight, but scratches are thin at 750g weight Class C: Scratches appear thin at 400g weight, and scratches are clearly visible at 750g weight D Grade: Scratches are clearly visible at 400g and 750g.

(10) Evaluation of shaving of the light guide plate From the backlight A, a light guide plate (acrylic plate, 4 mm thickness) provided with a convex portion on one side is taken out, and on the surface side where the convex portion of the obtained light guide plate is provided, after the surface of the particles containing layer is laminated reflective film are laminated so as to contact, and laminated under a load of ^{50gf / cm 2, 175gf / cm} 2, a reflection film sample at a linear velocity of 1 m / min, The film was pulled in the direction perpendicular to the thickness direction of the reflective film. Thereafter, the degree of scratches generated on the convex portions of the light guide plate was observed using a Keyence Corporation laser microscope VK-9710 with a magnification of the objective lens of 20 and a display magnification of 100%. The evaluation was based on the following criteria.
Class A: No scratches are seen under any load.
Class B: 175gf / cm ² of but scratches is observed under load, not seen wounds under a load of 50 gf / cm ^2.

Example 1
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 180 g, ethyl acetate 236.4 g, diameter in the range of 25 to 50 μm Nylon resin particles containing particles (SP20 manufactured by Toray Industries, Inc., volume average particle size 30 μm) 12 g, acrylic resin particles containing particles having a diameter in the range of 1 to 15 μm (“TECHPOLYMER” manufactured by Sekisui Plastics Co., Ltd.) 16 g of (registered trademark) MBX5, volume average particle diameter 5 μm) were mixed and stirred to prepare a coating solution. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Example 2)
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 180 g, ethyl acetate 236.4 g, diameter in the range of 25 to 50 μm Polyethylene resin particles containing particles (molecular weight 200 × 10 ⁴ , melting point 136 ° C., volume average particle diameter 30 μm) 12 g, acrylic resin particles containing particles having a diameter in the range of 1 to 15 μm (manufactured by Sekisui Plastics Co., Ltd.) A coating solution was prepared by stirring 16 g of “TECHPOLYMER” (registered trademark) MBX5, volume average particle diameter 5 μm). This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute. The molecular weight of the polyethylene resin particles was converted from IV [η] (dl / g), and the melting point was calculated according to ASTM D 3418.

(Example 3)
"HALS HYBRID" (registered trademark) UV-G720T (acrylic copolymer, 40 mass% solution, manufactured by Nippon Shokubai Co., Ltd.) 180 g, ethyl acetate 236.4 g, polyethylene resin particles 12 g used in Example 2 Then, 16 g of nylon resin particles (SP500 manufactured by Toray Industries, Inc., volume average particle size 5 μm) containing particles having a diameter in the range of 1 to 15 μm were stirred to prepare a coating solution. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

Example 4
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 180 g, ethyl acetate 236.4 g, diameter in the range of 25 to 50 μm Nylon resin particles containing particles (SP20 manufactured by Toray Industries, Inc., volume average particle size 30 μm) 12 g, polyethylene resin particles containing particles having a diameter in the range of 1 to 15 μm (molecular weight 180 × 10 ⁴ , melting point 136 ° C., volume A coating solution was prepared by stirring 16 g of an average particle size of 5 μm. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute. The molecular weight of the polyethylene resin particles was converted from IV [η] (dl / g). The melting point was calculated according to ASTM D 3418.

(Example 5)
"HALS HYBRID" (registered trademark) UV-G720T (acrylic copolymer, 40 mass% solution, manufactured by Nippon Shokubai Co., Ltd.) 180 g, ethyl acetate 236.4 g, polyethylene resin particles 12 g used in Example 2 Then, 16 g of the polyethylene resin particles used in Example 4 were stirred to prepare a coating solution. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Example 6)
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 180 g, ethyl acetate 236.4 g, diameter in the range of 25 to 50 μm Nylon resin particles containing particles (SP20 manufactured by Toray Industries, Inc., volume average particle diameter 30 μm) 12 g, nylon resin particles containing particles having a diameter in the range of 1-15 μm (SP500 manufactured by Toray Industries, Inc., volume average particle diameter) A coating solution was prepared by stirring 16 g of 5 μm). This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Example 7)
“Hals Hybrid” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 110 g, ethyl acetate 278.4 g, diameter within the range of 25 to 50 μm Nylon resin particles containing particles (SP20 manufactured by Toray Industries, Inc., volume average particle diameter 30 μm) 40 g, nylon resin particles containing particles having a diameter in the range of 1-15 μm (SP500 manufactured by Toray Industries, Inc., volume average particle diameter) A coating solution was prepared by stirring 16 g of 5 μm). This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Example 8)
“Hals Hybrid” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 110 g, ethyl acetate 278.4 g, diameter within the range of 25 to 50 μm 40 g of nylon resin particles containing particles (volume average particle diameter of 40 μm) and 16 g of nylon resin particles containing particles having a diameter in the range of 1 to 15 μm (SP500 manufactured by Toray Industries, Inc., volume average particle diameter of 5 μm) were stirred. A coating solution was prepared. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

Example 9
“Harus Hybrid” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 202.5 g, ethyl acetate 222.9 g, diameter in the range of 25-50 μm Nylon resin particles (SP20 manufactured by Toray Industries, Inc., volume average particle diameter 30 μm), nylon resin particles containing particles having a diameter in the range of 1 to 15 μm (SP10 manufactured by Toray Industries, Inc., volume average) A coating solution was prepared by stirring 10 g of a particle diameter of 10 μm. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Example 10)
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 207.5 g, ethyl acetate 219.9 g, diameter within the range of 25-50 μm Resin particles (SP20 manufactured by Toray Industries, Inc., volume average particle diameter 30 μm), nylon resin particles containing particles having a diameter in the range of 1-15 μm (SP10 manufactured by Toray Industries, Inc., volume average) A coating solution was prepared by stirring 10 g of a particle diameter of 10 μm. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Example 11)
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 107.5 g, ethyl acetate 724.4 g, diameter in the range of 25-50 μm 22 g of nylon resin particles (volume average particle diameter of 50 μm) containing 35 g of particles and 35 g of nylon resin particles (SP500 manufactured by Toray Industries, Inc., volume average particle diameter of 5 μm) containing particles having a diameter in the range of 1 to 15 μm are stirred. The coating liquid was prepared. This coating solution was applied to one side of a 300 μm thick porous biaxially stretched polyethylene terephthalate white film (base film, “Lumirror” (registered trademark) E6SQ manufactured by Toray Industries, Inc.) using Metabar # 40. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Example 12)
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 207.5 g, ethyl acetate 219.9 g, diameter within the range of 25-50 μm 7 g of nylon resin particles (volume average particle diameter 25 μm) containing particles in the above, and 10 g of nylon resin particles (SP10 manufactured by Toray Industries, Inc., volume average particle diameter 10 μm) containing particles having a diameter in the range of 1 to 15 μm are stirred. The coating liquid was prepared. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Example 13)
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40 mass% solution, manufactured by Nippon Shokubai Co., Ltd.) 87.5 g, ethyl acetate 736.4 g, nylon resin particles (volume average particle diameter) The coating liquid was prepared by stirring 55 g of 60 μm) and 10 g of nylon resin particles (volume average particle diameter 2 μm). This coating solution was applied to one side of a 300 μm thick porous biaxially stretched polyethylene terephthalate white film (base film, “Lumirror” (registered trademark) E6SQ manufactured by Toray Industries, Inc.) using Metabar # 40. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Example 14)
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40 mass% solution, manufactured by Nippon Shokubai Co., Ltd.) 37.5 g, ethyl acetate 321.9 g, nylon resin particles (volume average particle diameter) A coating solution was prepared by stirring 55 g of 20 μm) and 30 g of nylon resin particles (volume average particle diameter of 15 μm). This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Example 15)
“Harus Hybrid” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 102.5 g, ethyl acetate 282.9 g, diameter within the range of 25-50 μm 35 g of nylon resin particles (particles having a volume average particle diameter of 25 μm) and particles of nylon resin particles having a diameter in the range of 1 to 15 μm (SP500 manufactured by Toray Industries, Inc., volume average particle diameter of 5 μm) are stirred. The coating liquid was prepared. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Comparative Example 1)
"Hals Hybrid" (registered trademark) UV-G720T (acrylic copolymer, solution having a concentration of 40% by mass, manufactured by Nippon Shokubai Co., Ltd.) 210 g, ethyl acetate 218.4 g, diameter in the range of 25 to 50 μm Nylon resin particles containing particles (SP20 manufactured by Toray Industries, Inc., volume average particle diameter 30 μm) 6 g, nylon resin particles containing particles having a diameter in the range of 1-15 μm (SP500 manufactured by Toray Industries, Inc., volume average particle diameter) 5 μm) was stirred to prepare a coating solution. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Comparative Example 2)
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40 mass% solution, manufactured by Nippon Shokubai Co., Ltd.) 62.5 g, ethyl acetate 306.9 g, nylon resin particles (Toray Industries, Inc.) A coating solution was prepared by stirring 65 g of SP20 manufactured, volume average particle size 30 μm) and 10 g of nylon resin particles (SP500 manufactured by Toray Industries, Inc., volume average particle size 5 μm). This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Comparative Example 3)
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 175 g, ethyl acetate 239.4 g, acrylic resin particles (Sekisui Plastics Co., Ltd.) ) SSX-127 manufactured, volume average particle diameter 27 μm) 30 g was stirred to prepare a coating solution. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Comparative Example 4)
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, solution with a concentration of 40% by mass, manufactured by Nippon Shokubai Co., Ltd.) 100 g, ethyl acetate 284.4 g, nylon resin particles (SP20 manufactured by Toray Industries, Inc.) And 6 g of nylon resin particles (SP500 manufactured by Toray Industries, Inc., 5 μm of volume average particle diameter) were stirred to prepare a coating solution. This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

(Comparative Example 5)
“HALS HYBRID” (registered trademark) UV-G720T (acrylic copolymer, 40% by weight solution, manufactured by Nippon Shokubai Co., Ltd.) 12.5 g, ethyl acetate 336.9 g, nylon resin particles (Toray Industries, Inc.) A coating solution was prepared by stirring 60 g of SP20 manufactured, volume average particle size 30 μm) and 35 g of nylon resin particles (SP500 manufactured by Toray Industries, Inc., volume average particle size 5 μm). This coating liquid was applied to one side of a white film (base film, “Lumirror” (registered trademark) E6SQ, manufactured by Toray Industries, Inc.) made of porous biaxially stretched polyethylene terephthalate having a thickness of 300 μm using Metabar # 20. The coating layer was provided under drying conditions at 120 ° C. for 1 minute.

  The base film provided with the coating layer obtained in each example and each comparative example was evaluated as a reflective film. The coating layer in the examples corresponds to the particle-containing layer. In addition, even when the volume average particle size described in the examples is not in the range of 25 to 50 μm and 1 to 15 μm, since the particle size distribution exists in the particle, the particle containing layer has a particle size of 25 to 50 μm. There are particles having a diameter of 1 to 15 μm.

Table 1 shows the particle material, the ratio of particles in the particle-containing layer, and the mass per 1 m ^{2 of the} particle-containing layer.

  In Table 2, SRz, the presence of particles having a particle size of 25 to 50 μm, the presence of particles having a particle size of 1 to 15 μm, and independently exist without contacting the convex portion having a diameter of 25 to 50 μm. The number of convex portions having a diameter of ˜50 μm and the determination of whether or not the number of convex portions included in the aggregate of convex portions with which the convex portions having a diameter of 25 to 50 μm continuously contact are 10 or less are described.

Table 3 shows the results of particle dispersibility, reflection film scratching, light guide plate shaving evaluation, and white spot unevenness evaluation.
Each of the reflective films of the examples having the characteristics of the present invention had better evaluation results with a reflective film scratch than the reflective film of the comparative example.

DESCRIPTION OF SYMBOLS 1 Reflective film 2 Light guide plate 3 Light emitting diode 4 Back surface housing 5 Light guide plate convex part 6 Light guide plate concave part 7 Back surface concave part

Claims (4)

A particle-containing layer containing a base film and particles having a particle diameter of 25 to 50 μm and particles having a particle diameter of 1 to 15 μm;
An edge-light-type reflective film for a backlight, at least one of which satisfies the following requirements (i) to (iii):
(I) There is a convex part having a diameter of 25 to 50 μm.
(Ii) The number of convex portions having a diameter of 25 to 50 μm is 10 to 100 per 0.64 mm ^2, which is present independently without contacting convex portions having a diameter of 25 to 50 μm.
(Iii) When the range of 0.64 mm ² is observed , the number of convex portions included in the aggregate of convex portions with which the convex portions having a diameter of 25 to 50 μm continuously contact is 10 or less on average . The reflective film for an edge light type backlight according to claim 1, wherein the surface satisfying the requirements of (i) to (iii) is a surface of the particle-containing layer. The reflective film for edge light type backlight according to claim 1 or 2, wherein SRz of the surface satisfying the requirements of (i) to (iii) is 15 to 60 µm. The edge light type backlight using the reflective film for edge light type backlights in any one of Claims 1-3.