JP5089461B2 - Transflective reflective film, backlight for liquid crystal display, and method for producing transflective reflective film - Google Patents

Description

  The present invention relates to a transflective film that transmits part of incident light and reflects the remaining light. The present invention also relates to a backlight for a liquid crystal display using the transflective film and a method for producing the transflective film.

  In recent years, mobile phones are provided with a display called a dual liquid crystal display having a sub liquid crystal panel on the back side of a main liquid crystal panel. In such a dual liquid crystal display, a prism sheet, a light guide plate, and a reflective film are laminated on each of the main liquid crystal panel and the sub liquid crystal panel, and a backlight for a liquid crystal display having a light source on the side surface of the light guide plate is provided. It has been. This reflective film is formed by melt-extruding polyethylene terephthalate (PET) kneaded with a white filler that reflects light (for example, see Patent Document 1) or by providing a transparent film with a pigment layer. (For example, refer to Patent Document 2).

  By the way, for the purpose of thinning the cellular phone, the main liquid crystal panel and the sub liquid crystal panel are not provided with a backlight, but a liquid crystal that irradiates both the main liquid crystal panel and the sub liquid crystal panel with the light of one backlight. A display has been developed. In the backlight of such a liquid crystal display, it is necessary to transmit a part of the light from the light source guided by the light guide plate and reflect the remaining light, and it is not possible to use the reflection film as described above. Therefore, a transflective film that reflects part of the light and transmits the remaining light is used. As such a transflective reflection film, there is one formed by melt extrusion by heat in the same manner as the above reflection film. Then, a translucent reflection film has been developed in which a pigment layer is formed on a transparent film, and a part of incident light is transmitted and the remaining light is reflected (for example, see Patent Document 3).

JP-A-3-50241 JP 2003-59324 A JP 2004-271541 A

  As described above, when the transflective film is formed by melt extrusion with heat, foreign substances such as resin such as PET and agglomerates of white filler are mixed in. Therefore, light transmitted through the transflective film is not transmitted. It is obstructed by foreign matter and affects the image quality. In the case of a transflective reflective film formed by melt extrusion, the reflectance and the transmittance depend on the thickness of the film, so that the degree of freedom in selecting the thickness is low. In particular, when the film is made thinner, the transmittance increases and the reflectance decreases, which causes a problem that the luminance of one of the liquid crystal displays decreases.

  Further, in the case of Patent Document 3, the reflectance and transmittance can be adjusted, and a transflective film with few foreign matters can be formed. In this semi-transmissive reflective film, the surface of the pigment layer formed of a single pigment is smooth, so that the semi-transmissive reflective film and the optical member are in close contact with each other. However, in order to apply this transflective film to a liquid crystal display for displaying a high-quality image, it is necessary to make the surface in contact with the optical member rough.

  Therefore, the inventors of the present invention have conducted intensive research in view of the above problems. Therefore, the present invention enables the thinning of a backlight used in a liquid crystal display having a liquid crystal panel on both sides, and transmits a part of light incident from a light source and reflects the remaining light. It is a first object of the present invention to provide a film, a manufacturing method thereof, and a backlight for a liquid crystal display using the transflective film. Also provided are a semi-transmissive reflective film having a rough surface that contacts an optical member such as a prism sheet, and a method for producing the same, and a backlight for a liquid crystal display using the semi-transmissive reflective film. Is the second purpose.

The transflective film of the present invention that achieves the above object contains a plurality of fillers, and has an average reflectance (A) of light having a wavelength of 400 nm or more and 700 nm or less, and a transmittance of light having a wavelength of 550 nm (B). And a ratio (A / B) of 3/1 or more and 6/1 or less is provided on at least one surface of the transparent film, and the total thickness is 60 μm or less. A white white filler that reflects, a rough surface-forming filler that roughens the surface of the transflective layer, and a resin that bonds the white filler and the rough surface-forming filler together to the transparent film , The average particle diameter of the white filler is 0.2 μm or more and 2 μm or less, the thickness of the semi-transmissive reflective layer is 5 μm or more and 30 μm or less, and the thickness of the rough surface-forming filler with respect to the thickness of the semi-transmissive reflective layer Average particle size 1/20 or less and 2/3 or less, the average particle diameter of the rough surface forming filler is larger than the average particle diameter of the white filler, and the ten-point average height Rz of the surface of the transflective layer is 3500 nm or more. It is characterized by being.

  The transflective film of the present invention contains a plurality of fillers, so that the ratio between the average reflectance (A) of light having a wavelength of 400 nm or more and 700 nm or less and the transmittance (B) of light having a wavelength of 550 nm ( The surface of the transflective layer having A / B) of 3/1 or more and 6/1 or less is a rough surface. And the total thickness of the film formed shall be 60 micrometers or less, and the thickness reduction of the backlight used for the display which has a liquid crystal panel on both surfaces is attained.

The backlight for a liquid crystal display of the present invention contains a plurality of fillers, and a ratio between an average reflectance (A) of light having a wavelength of 400 nm or more and 700 nm or less and a transmittance (B) of light having a wavelength of 550 nm ( A / B) is provided with a transflective layer having a thickness of 3/1 or more and 6/1 or less on at least one surface of the transparent film, the total thickness is 60 μm or less, and the plurality of fillers are white light reflecting light A white filler, a rough surface-forming filler that roughens the surface of the transflective layer, and a resin that bonds the white filler and the rough surface-forming filler together to the transparent film . The average particle size is 0.2 μm or more and 2 μm or less, the thickness of the transflective layer is 5 μm or more and 30 μm or less, and the average particle size of the rough surface forming filler with respect to the thickness of the semitransparent reflective layer is 1 / 20 or more and 2/3 or less, the average particle size of the rough surface forming filler is larger than the average particle size of the white filler, and the ten-point average height Rz of the surface of the transflective layer is 3500 nm or more. A transflective film, and a light guide plate that is superimposed on the transparent film of the transflective film and emits light incident from a light source to a contact surface with the transparent film and a surface opposite to the contact surface And a prism sheet provided to sandwich the transflective film and the light guide plate.

  The backlight for a liquid crystal display according to the present invention enables the light from the light source to be emitted from both sides of the backlight by the above-described transflective film, and irradiates the liquid crystal panel on both sides with one backlight. can do. The transflective reflective film can reduce the backlight of the liquid crystal display.

Further, the method for producing a transflective film of the present invention comprises a white white filler that reflects light, a rough surface-forming filler that has a rough surface on the semi-transmissive reflective layer, the white filler, and the rough surface formation. A step of preparing a coating liquid by mixing a plurality of fillers having a resin for adhering the filler together with a transparent film in a solvent, and a step of filtering the prepared coating liquid with a filter having a filtration accuracy of 10 μm or more and 150 μm or less. And the filtered coating liquid is applied to at least one main surface of the transparent film and dried so that the total thickness after drying is 60 μm or less, and the average reflectance of light having a wavelength of 400 nm or more and 700 nm or less and (a), the ratio of the transmittance of light with a wavelength of 550nm (B) (a / B ) is 3/1 or more, and a step of forming a semitransparent reflective layer, which is a 6/1 or less, the white Filler The average particle size is 0.2 μm or more and 2 μm or less, the thickness of the transflective layer is 5 μm or more and 30 μm or less, and the average particle size of the rough surface forming filler with respect to the thickness of the semitransparent reflective layer is 1/20 or less and 2/3 or less, the average particle diameter of the rough surface forming filler is larger than the average particle diameter of the white filler, and the ten-point average height Rz of the surface of the transflective layer is 3500 nm or more. It is characterized by being.

  By this method, the surface of the semi-transmissive reflective layer becomes rough, and it becomes possible to produce a semi-transmissive reflective film that can realize thinning of the backlight. Unlike a film formed by kneading a white filler and melt-extrusion, this method for producing a transflective reflective film can reduce the possibility of contamination.

  In the present invention, by including a plurality of fillers, the ratio (A / B) of the average reflectance (A) of light having a wavelength of 400 nm to 700 nm and the transmittance (B) of light having a wavelength of 550 nm is 3 The surface of the transflective layer that is 1/1 or more and 6/1 or less is a rough surface, and the total thickness of the transflective film is 60 μm or less, so that the backlight can be thinned. Further, the present invention makes it possible to produce this transflective reflective film, and a backlight for a liquid crystal display having this transflective reflective film can irradiate light on a liquid crystal panel on both sides. Thinning of the light can be realized.

  Hereinafter, the manufacturing method of the transflective film, the backlight for a liquid crystal display, and the transflective film of the present invention will be described. Note that the present invention is not limited to the following description, and can be appropriately changed without departing from the spirit of the present invention.

  As shown in FIG. 1, the transflective film 10 of the present invention includes a transparent film 2 and a transflective layer 1 formed on at least one surface of the transparent film 2. The transflective layer 1 contains a plurality of fillers, transmits a part of the incident light, and reflects the remaining light. Since the transflective layer 1 contains a plurality of fillers, one surface that does not contact the transparent film 2 is a rough surface.

  The transflective film 10 preferably has a total thickness of 60 μm or less. If the transflective film 10 exceeds 60 μm, it will hinder the thinning of the backlight.

  The transparent film 2 is a transparent film having a predetermined size. The material of the transparent film 2 is not particularly limited as long as it transmits incident light, and examples thereof include polyester, polyphenylene sulfide, polyethylene naphthalate, polyimide, polyethylene, and polypropylene. Especially, the film which made polyester the material from a viewpoint of transparency and a physical characteristic is preferable.

  The thickness of the transparent film 2 is not particularly limited, but is preferably in the range of 5 μm to 30 μm. When the transparent film 2 is less than 5 μm, the film loses its elasticity, and as shown below, wrinkles and the like occur when applying the coating liquid for forming the semi-transmissive reflective layer 1, and uniform semi-transmissive The reflective layer 1 cannot be formed. On the other hand, when the transparent film 2 exceeds 50 μm, it is difficult for the total thickness of the transflective reflective film 10 to be 60 μm or less.

  The transflective layer 1 has a white white filler that reflects light, a rough surface forming filler that has a rough surface, and a resin that adheres the plurality of fillers to the transparent film 2 dispersed or dissolved in a solvent. It is formed by applying and drying the coating liquid on the transparent film 2. Since the transflective layer 1 contains a plurality of fillers, the surface opposite to the surface in contact with the transparent film 2 in the transflective layer 1 becomes a rough surface.

  The transflective layer 1 preferably has a thickness of 5 μm or more and 30 μm or less after the coating liquid is applied to the transparent film 2 and dried. When the semi-transmissive reflective layer 1 is less than 5 μm, the semi-transmissive reflective layer 1 is too thin, so that the light reflectance is lowered. That is, when used as a backlight of a display having a liquid crystal panel on both sides, it becomes impossible to irradiate one of the liquid crystal panels with sufficient light, and sufficient luminance cannot be obtained. On the other hand, when the semi-transmissive reflective layer 1 exceeds 30 μm, it becomes difficult for the total thickness of the semi-transmissive reflective film 10 to be 60 μm or less.

  Further, the transflective layer 1 has a ratio (A / B) of 3/1 or more of the average reflectance (A) of light having a wavelength of 400 nm or more and 700 nm or less and the transmittance (B) of light having a wavelength of 550 nn. 6/1 or less. When the ratio (A / B) between the average reflectance and the transmittance of the transflective layer 1 does not satisfy 3/1 or more and 6/1 or less, either one of the backlights of the display having a liquid crystal panel on both sides The liquid crystal panel cannot be irradiated with sufficient light, and sufficient luminance cannot be obtained. For example, it is used for a backlight of a display having a main liquid crystal panel on the side irradiated with light reflected by the semi-transmissive reflective layer 1 and a sub-liquid crystal panel on the side irradiated with light transmitted through the semi-transmissive reflective layer 1 In this case, when the ratio (A / B) between the average reflectance and the transmittance of the transflective layer 1 is less than 3/1, it becomes impossible to irradiate the main liquid crystal panel with sufficient light. On the other hand, when the ratio (A / B) between the average reflectance and the transmittance of the transflective layer 1 exceeds 6/1, it becomes impossible to irradiate the sub liquid crystal panel with sufficient light. The ratio (A / B) between the reflectance and the transmittance of the transflective layer 1 is appropriately determined by changing the type, particle size and content of the white filler, the thickness of the transflective layer 1 and the like as shown below. It can be adjusted by changing.

  Further, the surface of the transflective layer 1 preferably has a ten-point average height Rz of 3500 nm or more. When the ten-point average height Rz of the surface of the transflective layer 1 is less than 3500 nm, the surface is not sufficiently rough, and a portion that adheres closely to another optical member stacked on the transflective film (adhesion) Unevenness) is formed, resulting in uneven brightness.

  The ten-point average roughness Rz according to the present invention is defined by JIS surface roughness (B0601). This 10-point average roughness Rz is the difference between the average value of the top elevation from the highest to the fifth and the average elevation of the bottom from the deepest to the fifth in the part extracted by the reference length from the cross-section curve. It represents.

  The transflective layer 1 contains, as a plurality of fillers, a white white filler that reflects light and a rough surface forming filler that has a rough surface that does not contact the transparent film 2 in the transflective layer 1. The white filler may be any white particle that reflects light, and examples thereof include particles made of a material such as titanium dioxide, barium sulfate, zinc oxide, and zirconia oxide.

  The white filler preferably has an average particle size of 0.2 μm or more and 2 μm or less. If the average particle diameter of the white filler is within this range, it is difficult to cause unevenness and wrinkles when applying a coating liquid for forming the transflective layer 1 on the transparent film, and the uniform transflective layer 1 is formed. can do.

  Moreover, it is preferable that content of this white filler shall be 40 wt% or more and 70 wt% or less with respect to resin shown below. When the content of the white filler is less than 40 wt%, the light reflectance becomes low. On the other hand, when the content of the white filler is more than 70 wt%, the amount of the white filler is too large and the strength becomes insufficient and the transflective layer 1 becomes brittle, and the transflective layer 1 is cracked, chipped or peeled off. Such a problem will occur.

  The white filler may be a substantially spherical particle or may be a flat particle. Moreover, although the white filler contained in the semi-transmissive reflective layer 1 may be one type, a plurality of types made of different materials may be used.

  The rough surface forming filler contained in the transflective layer 1 together with the white filler is, for example, an inorganic filler such as silica, talc, alumina, calcium carbonate, mica, or an organic filler such as acrylic resin, benzoguanamine resin, melanin resin, or silicone resin. And particles made of such materials.

  The rough surface forming filler has an average particle size of 1/20 or more and 2/3 or less with respect to the thickness of the semi-transmissive reflective layer 1 formed by including a white filler and a rough surface forming filler. Preferably there is. When the rough surface-forming filler is less than 1/20 with respect to the thickness of the transflective layer 1, it is difficult to form a rough surface on the surface of the transflective layer 1, and the other surface is superimposed on the transflective film. Unevenness of contact with the optical member is formed, resulting in uneven brightness. On the other hand, when the rough surface forming filler exceeds 2/3 with respect to the thickness of the transflective layer 1, a coating streak occurs when it is applied to the transparent film 2 together with the white filler and the resin, and uniform transflective reflection occurs. Layer 1 cannot be formed.

  Further, the content of the rough surface forming filler is not particularly limited as long as a rough surface can be formed on the transflective layer 1 by being applied to the transparent film 2. If the resin shown below contains, for example, about 5 wt%, the semi-transmissive reflective layer 1 having a rough surface can be formed.

  The rough surface-forming filler may be substantially spherical particles, but may be flat particles. Moreover, the rough surface forming filler contained in the semi-transmissive reflective layer 1 may be one type, but may be a plurality of types made of different materials.

  The resin for adhering the white filler and the rough surface forming filler to the transparent film 2 is not particularly limited, and examples thereof include polyester, polyvinyl butyral, polyacetal, acrylic, epoxy, and urethane. This resin preferably has a glass transition temperature Tg of 20 ° C. or higher. If a resin having a glass transition temperature Tg of less than 20 ° C. is used, uneven adhesion with other optical members stacked on the transflective reflective film is formed, resulting in uneven brightness.

  The white filler, the rough surface forming filler and the resin are dissolved and dispersed in a solvent to form a coating solution. The solvent used here is not particularly limited as long as the white filler and the rough surface forming filler are dispersed and the resin is dissolved. Examples of the solvent include methyl ethyl ketone, toluene, isopropyl alcohol, methyl isobutyl alcohol, ethyl acetate, butyl acetate, xylene, cyclohexanone and the like.

  Thus, the transflective film 10 of the present invention is a transflective layer 1 containing a white filler and a rough surface forming filler as a plurality of fillers, and transmits part of the light and reflects the remaining light. can do. And when the total thickness of the formed film is 60 μm or less, the backlight can be made thinner. Furthermore, the surface of the transflective layer 1 becomes a rough surface by containing a plurality of fillers. That is, by applying the transflective film 10 to a backlight used for a display having a liquid crystal panel on both sides, a single light source can be irradiated on the liquid crystal panel on both sides, thereby providing a thin liquid crystal display. can do.

  The transflective film 10 having the transflective layer 1 can be manufactured as follows. First, a white filler, a rough surface forming filler, and a resin are mixed in a solvent to obtain a coating solution. At this time, the resin is dissolved in the solvent, and the white filler and the rough surface forming filler are dispersed in the solvent in which the resin is dissolved. The prepared coating liquid is filtered through a filter having a filtration accuracy of 10 μm or more and 150 μm or less. Foreign substances can be removed by this filtration. If the foreign matter is present in the transflective reflective film 10, the transmitted light is blocked, so that the image quality is deteriorated in the liquid crystal display. In the method of the present invention, the foreign matter can be removed by the filter, so the image quality is not deteriorated by the foreign matter.

  The coating liquid filtered by the filter is applied to at least one of the transparent films 2 by a predetermined method so that the thickness after application and drying satisfies the above range. This coating method is not particularly limited as long as it is a method capable of forming the uniform transflective layer 1 on the transparent film 2, and for example, a kiss coating method, a bar coating method, a die coating method, a reverse coating method, An offset gravure coating method, a Myer bar coating method, a gravure coating method, a roll brush method, a spray coating method, an air knife coating method, a soaking method and a curtain coating method can be applied alone or in combination. And the coating liquid apply | coated on the transparent film 2 can be dried, the transflective layer 1 can be formed on the transparent film 2, and the transflective film 10 can be manufactured.

  By this method, it is possible to manufacture the transflective film 10 that can make the surface of the transflective layer 1 rough and realize a thin backlight. In addition, unlike a film formed by kneading a white filler and melt extrusion, the possibility of contamination is reduced.

  Next, the backlight for a liquid crystal display of the present invention will be described. As shown in FIG. 2, the backlight 20 for a liquid crystal display according to the present invention is formed by laminating a light guide plate 11 and optical members such as prism sheets 12 and 13 on the transflective film 10, and a light source 14 of the light guide plate 11. Provided on the side.

  The backlight 20 for a liquid crystal display of the present invention is superposed so that the surface of the transflective reflective film 10 on the transparent film 2 side is brought into contact with one main surface of the light guide plate 11. The light guide plate 11 guides light incident from the light source 14 provided on the side surface of the light guide plate 11 in a direction perpendicular to the laminating direction, and the contact surface with the transflective film 10 and the contact surface thereof. Light is emitted to the opposite surface. Examples of the light source 14 include a light emitter such as an LED (Light Emitting Diode), and irradiates the light guide plate 11 with light from the side surface of the light guide plate 11.

  The superposed light guide plate 11 and semi-transmissive reflective film 10 are provided with prism sheets 12 and 13 so as to sandwich the light guide plate 11 and the semi-transmissive reflective film 10. Specifically, the transflective layer 1 of the transflective film 10 is provided so as to be in contact with one prism sheet 13, and the light guide plate 11 on the opposite side of the surface in contact with the transflective film 10 is provided. The prism sheet 12 is provided in contact with the surface. The prism sheets 12 and 13 are light beams emitted from the light guide plate 11 to the main liquid crystal panel 15 and the sub liquid crystal panel 16 provided further outside the laminated transflective reflective film 10, the light guide plate 11 and the prism sheets 12 and 13. Is condensed and led to each liquid crystal panel. In addition, you may use other optical members, such as a diffusion sheet which diffuses light, for the backlight 20 for liquid crystal displays of this invention.

  First, light from the light source 14 enters from the side surface of the light guide plate 11 and is guided in a direction perpendicular to the stacking direction of the light guide plate 11, and also on the contact surface with the transflective film 10 and the contact surface thereof. On the other hand, the light is emitted from the opposite surface. Here, a part of the light emitted from the light guide plate 11 to the transflective reflective film 10 is reflected by the transflective reflective film 10 and is directed to the side opposite to the contact surface with the light guide plate 11, and the rest is left. The light passes through the transflective film 10 and travels toward the transflective layer 1 side. The light reflected by the transflective reflection film 10 passes through the light guide plate 11 and is irradiated onto the main liquid crystal panel 15 through the prism sheet 12. On the other hand, the light transmitted through the semi-transmissive reflective film 10 is irradiated to the sub liquid crystal panel 16 through the prism sheet 13. Thus, it functions as a backlight of a display having a liquid crystal panel on both sides.

  The backlight 20 for a liquid crystal display of the present invention can irradiate light to a liquid crystal panel provided on both sides by one, and the backlight can be thinned by including a transflective film 10 of 60 μm or less. Can be realized.

[Example]
In this example, the total thickness, the thickness of the transparent film, the thickness of the transflective layer, the ratio between the reflectance and the transmittance, the content of the white filler, the particle size of the rough surface forming filler, the glass transition temperature of the resin Evaluation was made on a transflective film formed by changing Tg and the ten-point average height Rz of the surface of the transflective layer.

  The semi-transmissive reflective film to be evaluated is a mixed solvent of methyl ethyl ketone and toluene using titanium oxide particles as a white filler, benzoguanamine / formaldehyde condensate particles as a rough surface forming filler, and polyvinyl butyral as a solvent. The coating solution was dissolved and dispersed in The prepared coating liquid was filtered through a filter having a filtration accuracy of 10 μm to remove foreign matters in the coating liquid, applied onto a PET film as a transparent film, and dried to obtain a transflective reflective film. In addition, the white filler used the particle | grains with an average particle diameter of 0.25 micrometer, and used 2 wt% of rough surface formation fillers with respect to resin. Total thickness of Examples 1 to 15 and Comparative Example, thickness of transparent film, thickness of semi-transmissive reflective layer, ratio of reflectance to transmittance, white filler content, particle size of rough surface forming filler, resin The glass transition temperature Tg and the ten-point average height Rz of the transflective layer surface are as shown in Table 1 or Table 2 below.

  The following evaluations were performed on Examples 1 to 15 and Comparative Examples shown in Table 1 or Table 2 below. In order to make the backlight for a liquid crystal display thinner, the total thickness of the transflective film needs to be 60 μm or less. In the evaluation regarding the influence on the backlight thinning, it was confirmed whether or not the total thickness of the transflective reflective film exceeded 60 μm. The case where the total thickness was 60 μm or less was rated as ◯, and the case where the total thickness exceeded 60 μm was marked as x.

  In the evaluation relating to the coating property of the transflective layer, when the coating liquid was applied to a transparent film, the appearance of the formed transflective reflective film was checked for wrinkles and distortion. The case where no wrinkles or distortion was confirmed was marked with ◯, and the case where wrinkles or distortion was confirmed was marked with ×. In the evaluation regarding the application shape of the semi-transmissive reflective layer, the presence or absence of streaks or bubbles was confirmed in the applied semi-transmissive reflective layer. The case where a streak or a bubble was not confirmed was marked with ◯, and the case where a streak or bubble was confirmed was marked with x.

  As shown in FIG. 2, when the main liquid crystal panel is irradiated with light reflected by the transflective reflection film, the reflectance needs to be 70% or more in order to obtain sufficient luminance. In the evaluation regarding the reflectance, it was confirmed whether or not the reflectance of the transflective reflective film was 70% or more. The case where the reflectance was 70% or more was rated as ◯, and the case where the reflectance was less than 70% was marked as x. When the sub-liquid crystal panel is irradiated with light transmitted through the transflective reflective film, the transmittance needs to be 15% or more in order to obtain sufficient luminance. In the evaluation of the transmittance, it was confirmed whether or not the transmittance of the transflective reflective film was 15% or more. The case where the transmittance was 15% or more was rated as ◯, and the case where the transmittance was less than 15% was marked as x. An ultraviolet-visible near-infrared spectrophotometer V670 (manufactured by JASCO Corporation) was used for the measurement of the reflectance and transmittance.

  In the evaluation regarding the strength of the transflective layer, an adhesive tape was applied to the surface of the transflective layer, and the adhesive tape was peeled off to confirm the strength of the transflective layer. When peeling or chipping is not confirmed on the transflective layer when the adhesive tape is peeled off, and when peeling or chipping is confirmed on a part of the transflective layer when the adhesive tape is peeled off Was evaluated as Δ, and the case where the same area as the adhesive tape was peeled off was marked as x.

  In the evaluation of the adhesion with the laminated film, a case where a PET film is placed on the surface of the transflective layer and the adhered part is not confirmed even after pressing the PET film against the transflective film by finger pressure several times The case where the contacted part was confirmed when the finger was pressed once was indicated by Δ, and the case where the contacted part was confirmed when pressed once was indicated by ×.

  As described above, in Examples 1 to 12, the surface of the semi-transmissive reflective layer is rough, and the total thickness of the semi-transmissive reflective film is 60 μm or less, so that the backlight can be thinned. . On the other hand, in Comparative Examples 1 and 5, the total thickness of the transflective film is 63 μm and 65 μm, and the backlight cannot be thinned. Further, it is clear from the comparison with Comparative Example 5 that Examples 1 to 12 are difficult to adhere to the film of the optical member due to the addition of the rough surface forming filler. In addition, Comparative Examples 2 and Comparative Example 1 to Example 12 have high characteristics as a transflective reflective film by adjusting the reflectance / transmittance to 3/1 to 6/1. It is clear from comparison with Example 3 and Comparative Example 4. Moreover, in Example 9, since the content of the white filler was as high as 80%, the applicability was lowered.

It is a figure which shows the structure of the transflective film of this invention. It is a figure which shows the structure of the liquid crystal display provided with the backlight of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transflective layer 2 Transparent film 10 Transflective film 11 Light guide plates 12 and 13 Prism sheet 14 Light source 15 Main liquid crystal panel 16 Sub liquid crystal panel 20 Backlight for liquid crystal display

Claims (5)

It contains a plurality of fillers, and the ratio (A / B) between the average reflectance (A) of light having a wavelength of 400 nm or more and 700 nm or less and the transmittance (B) of light having a wavelength of 550 nm is 3/1 or more, 6 / Provided with a transflective layer of 1 or less on at least one surface of the transparent film, the total thickness is 60 μm or less,
The plurality of fillers are white white fillers that reflect light, and
A rough surface-forming filler that roughens the surface of the transflective layer;
Having both the white filler and the rough surface forming filler adhered to the transparent film ,
The average particle size of the white filler is 0.2 μm or more and 2 μm or less,
The transflective layer has a thickness of 5 μm or more and 30 μm or less,
The average particle diameter with respect to the thickness of the semi-transmissive reflective layer of the rough surface forming filler is 1/20 or more and 2/3 or less,
The average particle size of the rough surface-forming filler is larger than the average particle size of the white filler, and the ten-point average height Rz of the surface of the transflective layer is 3500 nm or more. . The transflective reflective film according to claim 1, wherein the white filler has a content of 40 wt% to 70 wt% with respect to the resin. The transflective film according to claim 1, wherein the resin has a glass transition temperature Tg of 20 ° C. or higher. It contains a plurality of fillers, and the ratio (A / B) between the average reflectance (A) of light having a wavelength of 400 nm or more and 700 nm or less and the transmittance (B) of light having a wavelength of 550 nm is 3/1 or more, 6 / The transflective layer having a thickness of 1 or less is provided on at least one surface of the transparent film, the total thickness is 60 μm or less, and the plurality of fillers include a white white filler that reflects light and the surface of the transflective layer. It has a rough surface forming filler that is a rough surface, and a resin that adheres both the white filler and the rough surface forming filler to the transparent film, and the average particle size of the white filler is 0.2 μm or more and 2 μm or less. The thickness of the transflective layer is 5 μm or more and 30 μm or less, and the average particle diameter of the rough surface forming filler with respect to the thickness of the transflective layer is 1/20 or more and 2/3 or less, Rough surface forming filler The average particle size of the semi-transmissive reflective film is larger than the average particle size of the white filler, the ten-point average height Rz of the surface of the semi-transmissive reflective layer is 3500 nm or more,
A light guide plate that is superimposed on the transparent film of the transflective reflective film and emits light incident from a light source to a contact surface with the transparent film and a surface opposite to the contact surface;
A backlight for a liquid crystal display, comprising: the transflective reflective film; and a prism sheet provided so as to sandwich the light guide plate. A plurality of white white fillers that reflect light, a rough surface forming filler that roughens the surface of the transflective layer, and a resin that bonds the white filler and the rough surface forming filler together to a transparent film. A step of mixing a filler with a solvent to prepare a coating liquid;
Filtering the prepared coating liquid with a filter having a filtration accuracy of 10 μm or more and 150 μm or less;
By applying and drying the filtered coating solution on at least one main surface of the transparent film so that the total thickness after drying is 60 μm or less, the average reflectance (A of light having a wavelength of 400 nm or more and 700 nm or less) And a ratio (A / B) of the transmittance (B) of light having a wavelength of 550 nm to form a transflective layer having a ratio of 3/1 or more and 6/1 or less,
The average particle size of the white filler is 0.2 μm or more and 2 μm or less,
The transflective layer has a thickness of 5 μm or more and 30 μm or less,
The average particle diameter with respect to the thickness of the semi-transmissive reflective layer of the rough surface forming filler is 1/20 or more and 2/3 or less,
The average particle size of the rough surface-forming filler is larger than the average particle size of the white filler, and the ten-point average height Rz of the surface of the transflective layer is 3500 nm or more. Manufacturing method.