JP5369605B2 - White reflective film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white reflection film which improves the brightness of a liquid crystal backlight and is reduced in the deterioration of reflection ratio even when being used for a long period of time, and to provide a lamp reflector for backlight, an edge light type backlight and a direct backlight which use the white reflection film. <P>SOLUTION: The white reflection film is formed by laminating at least one layer of a resin layer containing a compound having at least one of a skeleton structure selected from a group consisting of five kinds of skeleton structures in a molecule and a non-porous spherical particles at least in one surface of a white film. The lamp reflector for backlight and the direct backlight are configured by providing the while reflection film so that its laminated surface is allowed to face the light source side. The edge light type backlight is configured by providing the white reflection film so that its laminated surface is allowed to face a light guide plate side. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a white reflective film for improving the luminance of a backlight for a liquid crystal display. More specifically, the present invention relates to a white reflector film used for a reflector of an edge light type backlight for a liquid crystal display, an edge light type and / or a direct type backlight for a liquid crystal display.

  In a liquid crystal display, a backlight that illuminates a liquid crystal cell is used. Depending on the type of liquid crystal display, the LCD monitor employs an edge light type backlight, and the liquid crystal television employs a direct type backlight. As a reflective film used for these backlights, a porous white film formed of bubbles is generally used (Patent Document 1). Furthermore, in order to prevent yellow discoloration of the film due to ultraviolet rays emitted from a lamp such as a cold cathode tube, a white film in which an ultraviolet absorbing layer is laminated has also been proposed (Patent Documents 2 and 3).

In a rapidly growing reflective film for liquid crystal televisions, cost reduction is strongly demanded, while improvement of the reflective properties of the reflective film is also demanded at the same time. This is because if the luminance as a backlight is improved by improving the reflection characteristics of the reflective film, the expensive sheet used on the upper part of the light source can be reduced. Therefore, various methods for improving various reflection characteristics in these reflective films have been disclosed. For example, there has been proposed a white film containing an extremely small amount of various fluorescent brighteners for the purpose of color adjustment in the ultraviolet absorbing layer laminated on the white film (Patent Documents 3 and 4). Furthermore, for the purpose of adjusting the glossiness of the surface together with these trace amounts of various optical brighteners, a method of adding porous or hollow particles or particles having a non-uniform shape has also been proposed (Patent Documents 5 and 6). Moreover, in order to improve the brightness in the edge light system, a method of providing a light shielding layer on the film surface opposite to the light source (Patent Document 7), or by selecting a difference in refractive index between the spherical particles and the binder A method for controlling the light diffusibility and improving the front luminance by the light diffusing sheet is disclosed (Patent Document 8).
JP-A-8-262208 JP 2001-166295 A JP 2002-90515 A JP 2006-48039 A JP 2005-173546 A Japanese Patent Laid-Open No. 2006-343864 JP 2002-333510 A JP 2001-324608 A

  However, although the reflection characteristics of the reflective film often depend on the void structure inside the white film, there is a limit to improving the reflection characteristics by devising the void structure as in Patent Document 1. Moreover, in the method of providing an ultraviolet absorption layer like patent documents 2-6, or containing a trace amount fluorescent brightening agent in the ultraviolet absorption layer, the absorbed ultraviolet energy is converted into heat, or the color of a reflective film It can only be converted into a small amount of light that contributes to adjustment, and it contains a small amount of fluorescent whitening agent and contains porous or hollow particles or particles with non-uniform shapes. Even the light contained by the contained particles is attenuated by refraction, reflection or scattering, and the luminance is not improved. Furthermore, since the methods as disclosed in Patent Documents 7 and 8 have little effect on the ultraviolet rays emitted from lamps such as cold cathode fluorescent lamps, these methods do not substantially increase the use efficiency of light energy as a backlight. After all, the reality is that the brightness has not been dramatically improved.

  In view of the background of such prior art, the present invention provides a white reflective film capable of improving the luminance of a liquid crystal backlight.

In order to solve this problem, the present invention employs the following configuration. That is, the white reflective film of the present invention has at least one kind selected from the group consisting of the following skeletal structures (1), (2), (3), (4) and (5) on at least one side of the white film. It is characterized in that at least one resin layer containing 3 to 75% by weight of a compound having a skeleton structure in the molecule and nonporous spherical particles is laminated.

本発明の白色反射フィルムの好ましい態様は、
（１） 前記化合物が、同一分子内に化１及び化２の構造を有するものであること、
（２） 前記化合物が、波長３００〜４５０ｎｍ間に極大吸収波長を有するものであること、
（３） 前記化合物が、波長３５０〜６００ｎｍ間に発光を有するものであること、
（４） 前記樹脂層中に、紫外線吸収剤および／または光安定化剤を含有することを特徴とするものである。

A preferred embodiment of the white reflective film of the present invention is
(1) The compound has the structures of Chemical Formula 1 and Chemical Formula 2 in the same molecule,
(2) The compound has a maximum absorption wavelength between wavelengths of 300 to 450 nm,
(3) The compound has light emission between wavelengths of 350 to 600 nm,
(4) The resin layer contains an ultraviolet absorber and / or a light stabilizer.

Further, the backlight lamp reflector and the direct type backlight of the present invention are configured such that the white reflective film of the present invention is provided with the surface on which the resin layer is laminated facing the light source side. It is a feature.
Further, the edge light type backlight of the present invention is characterized in that the white reflective film of the present invention is provided with the surface on which the resin layer is laminated facing the light guide plate side. It is.

  Moreover, the sealing film for solar cells of the present invention uses the white reflective film of the present invention for sealing a solar cell module.

  According to the present invention, by providing a specific resin layer on at least one side of a white film, a white reflective film in which the luminance of the backlight is improved when used for a backlight can be provided.

  In the white reflective film of the present invention, at least one resin layer containing a compound having a specific skeleton structure in the molecule and nonporous spherical particles is provided on at least one surface of the white film. The reason why the brightness of the backlight is greatly improved by incorporating the compound and nonporous spherical particles in such a resin layer is not clear, but the brightness in the front direction of the backlight is improved for the following reasons. It is estimated that there is.

  That is, for example, cold cathode tubes used for liquid crystal backlights generally have emission peaks in the ultraviolet region near 310 to 315 nm, the ultraviolet region near 360 to 370 nm, and the near ultraviolet region near 400 to 410 nm, and longer wavelengths than that. Since there are a plurality of emission peaks in the visible light region on the side, white light is reproduced by mixing each light. Here, by selecting a compound having a specific skeletal structure in the molecule, the light in the ultraviolet region, which hardly contributes to the luminance, of the light emitted from the cold cathode tube and the conventional ultraviolet absorber cannot be absorbed. It may be because it absorbs both the light in the near ultraviolet region and selectively converts to a wavelength different from the region having the effect of color adjustment, that is, a wavelength in the visible light region that contributes to luminance and emits it. Estimated. Further, by making the contained particles nonporous, it is possible to prevent the binder resin forming the resin layer from entering the particles. Therefore, not only the light in the visible light region emitted from the cold cathode tube, but also the light in the visible light region emitted by the compound having the specific skeleton structure in the molecule is repeatedly reflected and diffused at the interface between the binder resin and the particles. By reducing the amount of light that does not propagate to the front, the loss of light can be reduced to the limit. In addition, by making the contained non-porous particles spherical, the light in the visible light region that has been emitted from the cold cathode tube, reflected from the white film surface and transmitted through the resin layer, and the specific skeleton structure within the molecule It is estimated that the light in the visible light region emitted by the compound contained in the light is collected without losing the light due to the lens effect at the spherical part of the particle, and contributes to the improvement of the luminance in the front direction of the backlight . Further, this effect is not limited to the cold cathode tube, and the above effect can be exhibited if the light source or lamp has light emission in the ultraviolet region to the visible light region.

  The white reflective film of the present invention has at least one skeleton selected from the group consisting of the aforementioned skeleton structures (1), (2), (3), (4) and (5) on at least one side of the white film. At least one resin layer containing any one or more of compounds having a structure in the molecule and nonporous spherical particles is provided.

  When such a resin layer is not provided, when a compound having a specific skeleton structure in the molecule is not contained, or when non-porous spherical particles are not contained, even if the white reflective film is incorporated in the backlight, a brightness improvement effect is obtained. Or brightness improvement effect is small.

  The resin layer defined in the white reflective film of the present invention is a layer composed of a polymer compound containing an organic component and / or an inorganic component, and the form of the resin layer is a thin film on the white film, Although the composite layer etc. by the bonding of films are mentioned, it is not specifically limited to these.

  The compound contained in the resin layer according to the present invention needs to have at least one skeleton structure selected from skeleton structures (1) to (5) in the molecule. When none of the skeletal structures (1) to (5) is present, the brightness enhancement effect cannot be obtained. The skeletal structures of the skeletal structures (1) to (5) may be included in any bonding form, for example, various substituents, backbone structures, and covalent bonds with components constituting the resin layer such as a binder resin. , An ionic bond, a coordinate bond, or the like. In that sense, when they are contained in the resin layer, they may be contained alone, but they may be selected according to the application and characteristics, and are not particularly limited.

  Rn (n = 1 to 10) shown in the skeletal structures (1) to (5) of the compound according to the present invention is bonded to various substituents or molecules contained in a resin layer such as a backbone structure or a binder resin. Means. Basically, it is only necessary to have a skeletal structure represented by the skeletal structures (1) to (5) for exhibiting a brightness enhancement effect, and the productivity is good as long as the use and required characteristics are not hindered, Use arbitrarily selected substituents or bonding states that have good compatibility such as compatibility with the solvent used and the resin and additives used together, or mix two or more different substituents or bonding states, Further, an unsubstituted simple substance may be used, and it is not particularly limited. However, such a substituent is preferably a linear alkyl group such as a methyl group or an ethyl group, an iso-propyl group, or iso- Branched alkyl groups such as butyl group, sec-butyl, tert-butyl group, cyclic alkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, vinyl group, allyl group, hex An alkenyl group such as a nyl group, an aryl group such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group and a biphenyl group, an aralkyl group such as a benzyl group and a phenethyl group, an alkoxy group such as a methoxy group and an ethoxy group, and a sodium sulfonate group Such as sulfonic acid group, acrylic group, methacryl group, acryloxy group, methacryloxy group, oxycarbonyl group such as allyloxycarbonyl group / benzyloxycarbonyl group, epoxy group, isocyanate group, amino group / dimethylamino group / diethylamino group, etc. Substituted / unsubstituted amino groups, hydroxyl groups, carboxyl groups, halogen groups, and substituted / unsubstituted heterocyclic rings such as triazine, thiophenelactone, oxazole, and imidazole can be used.

  The particles contained in the resin layer according to the present invention must be nonporous spherical. When non-porous spherical particles are contained, a compound having a specific skeletal structure necessary for obtaining the same luminance as compared with the case of non-spherical spherical particles can be obtained with a significant improvement in luminance. Therefore, a great advantage can be obtained in terms of cost and productivity. If it is not non-porous or non-spherical, not only the brightness enhancement effect is small, but also the binder resin in the resin layer gets into the pores, the thickness of the resin layer becomes thin and specified When the white reflective film of the present invention is incorporated in a backlight, the light emitted from a lamp such as a cold cathode tube, particularly ultraviolet light, particularly the base white film or There is a possibility that the compound contained in the resin layer is deteriorated (for example, optical deterioration such as yellowing or decomposition deterioration that lowers the molecular weight).

  Here, nonporous means a state having no pores, and those having a plurality of pores on the particle surface are porous. The term “spherical” does not necessarily mean only a true sphere, but a particle whose cross-sectional shape is surrounded by a curved surface such as a circle, an ellipse, a substantially circle, or a substantially ellipse.

  Here, the “pores” and “shape” of the particles are obtained as follows.

  The sample is cut in a direction perpendicular to the film plane at a knife inclination angle of 3 ° using a rotary microtome manufactured by Nippon Microtome Laboratories. Using the scanning electron microscope ABT-32 manufactured by Topcon Corporation, the obtained film cross-section is, for example, at an observation magnification of 2500 to 10000 times, so that one particle is projected over the entire visual field region. The contrast is appropriately adjusted and observed, and the presence or absence of pores and the shape of the particles are judged.

  If the particles cannot be cut, immerse the resin layer in an organic solvent, peel off and collect the resin layer, and then press and slide on the slide glass to drop the particles from the resin layer and collect a sufficient amount of particles. . Subsequently, the obtained particles are used, for example, at an observation magnification of 2500 to 10,000 times, and an image so that one particle is projected over the entire visual field region using a scanning electron microscope ABT-32 manufactured by Topcon Corporation. The contrast is appropriately adjusted and observed, and the presence of pores and the shape of the particles are judged.

  Note that the presence / absence of pores is determined based on whether or not spots or spots are present in the particles in the observed image. No pores.

  As described above, the material of the particles may be any of an inorganic material, an inorganic compound, an organic compound, or a composite thereof as long as it is a non-porous spherical shape, and is not uniquely limited.

  The compound according to the present invention more preferably has both the skeleton structures (1) and (2) in the same molecule. When both of the skeleton structures (1) and (2) are included, a higher luminance improvement effect can be obtained as compared with the case where only one kind selected from the skeleton structures (1) to (5) is included. Although it is not clear why such a skeletal structure has the effect of further improving the brightness, it is possible to absorb ultraviolet rays emitted from a lamp such as a cold cathode tube more efficiently and in a wide wavelength region. It is presumed that light emission occurs even on the longer wavelength side and light in a wide wavelength range can be emitted, so that the utilization efficiency of substantial light energy is further improved. However, when a compound having both skeletal structures (1) and (2) is selected, depending on the type of additive and binder resin mixed together in the resin layer, and particularly the content in the resin layer Since it tends to cause yellowing, the chromaticity change of light generated from the backlight may occur strongly when used for a backlight for a liquid crystal display.

  On the other hand, in the case of having only one kind selected from the skeleton structures (1) to (5), the luminance improvement effect is lower than in the case of having both the skeleton structures (1) and (2), but the chromaticity change Since there is a tendency to reduce, use either by selecting one of them depending on the application or important characteristics, changing the content rate, or mixing one having both structures with one having only one type. can do.

  Specific examples of compounds having at least one or more skeleton structures selected from the group consisting of the skeleton structures (1) to (5) in the molecule include, for example, Eastobrite OB-1 (manufactured by Eastman Chemical Company). , Kayalight series (manufactured by Nippon Kayaku Co., Ltd.), Kayaphor series (manufactured by Nippon Kayaku Co., Ltd.), Mikawhite series (manufactured by Nippon Kayaku Co., Ltd.), UVITEX OB (manufactured by Ciba Specialty Chemicals Co., Ltd.) , Hostalux series (manufactured by Clariant Japan Co., Ltd.), Shigenox series (manufactured by Hakkor Chemical Co., Ltd.), Hakkol series (manufactured by Hakkor Chemical Co., Ltd.), Lumogen (registered trademark) F Violet 570 (manufactured by BASF), Lumogen (R) F Blue650 (manufactured by BASF), may be used Lumogen (TM) OB 433 (manufactured by BASF), etc., but it is not particularly limited thereto.

  The compound according to the present invention may be subjected to a surface treatment within a range that does not impair the effects of the invention from the viewpoints of improving dispersibility in the resin layer, maintaining stability, productivity, and the like.

  The compound according to the present invention preferably has a maximum absorption wavelength between wavelengths of 300 to 450 nm. In addition, the maximum absorption wavelength here is a wavelength at the maximum value of the absorption spectrum obtained by ultraviolet-visible spectrophotometry (UV-Vis) of a compound dissolved in a soluble solvent, and there are a plurality of maximum values. In some cases, any maximum absorption wavelength may exist between wavelengths of 300 to 450 nm. When the maximum absorption wavelength exists between wavelengths of 300 to 450 nm, even if the wavelength of light below the near ultraviolet region emitted from a lamp such as a cold cathode tube does not necessarily match the maximum absorption wavelength, the wavelength around the maximum absorption wavelength Since it has absorption in the region, it can be sufficiently converted into light in the visible light region.

  When the maximum absorption wavelength is on the shorter wavelength side than 300 nm, short wavelength light in the near ultraviolet region or less emitted from a lamp such as a cold cathode tube cannot be absorbed. Further, when the maximum absorption wavelength is on the longer wavelength side than 450 nm, not only the short-wavelength light below the near ultraviolet region emitted from the lamp such as a cold cathode tube can be absorbed, but also the lamp of the cold cathode tube or the like. Even light in the visible light region is absorbed, and conversely, there is a risk of causing a decrease in luminance and a significant change in chromaticity of backlight light.

  The compound according to the present invention preferably emits light at a wavelength of 350 to 600 nm. The light emission referred to here may be either fluorescence or phosphorescence, and is light generated when the absorbed light energy is emitted, and means that the entire emission spectrum exists between wavelengths of 350 to 600 nm. When light emission exists between wavelengths of 350 to 600 nm, the sensitivity of the perception is relatively high in the wavelength range of light that can be perceived by the general human eye, and the chromaticity change of the backlight light is not so large. As a result, the brightness of the backlight is improved, the chromaticity change of the screen is small, and a bright display can be achieved.

  When there is no light emission, the brightness enhancement effect cannot be obtained, and when the light emission wavelength is also in the short wavelength region shorter than 350 nm, the sensitivity that the general human eye can perceive becomes low, and even if light emission exists. In addition to recognizing that the brightness has not changed, the absorption wavelength region overlaps the emission wavelength region when two or more compounds with different concentrations or high concentrations are mixed. Since it becomes easy, the emitted light will be absorbed again and the brightness improvement effect may be low. Further, when light is emitted even in a wavelength region longer than 600 nm, there is a risk of causing a significant change in chromaticity of the backlight light. The emission wavelength is more preferably 380 to 550 nm.

  When the white reflective film of the present invention is used as a backlight, the white film of the substrate may be deteriorated by light emitted from a lamp such as a cold-cathode tube, particularly ultraviolet rays (for example, optical deterioration such as yellowing or low The binder resin that forms the resin layer provided on the white film of the base material contains an ultraviolet absorber and / or a light stabilizer within a range that does not impair the effects of the present invention. preferable. Note that the ultraviolet absorber has a little ultraviolet absorption band in a region that does not overlap with an absorption band in the ultraviolet region of a compound having at least one skeleton structure selected from skeleton structures (1) to (5) in the molecule. However, if what is possessed is selected, a compound having at least one skeletal structure selected from skeleton structures (1) to (5) in the molecule and the white film of the base material while exhibiting a brightness enhancement effect It is sufficiently possible to impart both effects, the effect of preventing deterioration due to ultraviolet rays.

  Although it does not specifically limit as binder resin which forms the resin layer concerning this invention, Resin which has an organic component as a main component is preferable, 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 and the like.

  These resins may be used alone, or two or more copolymers or a mixture thereof may be used. Among these, polyester resins, polyurethane resins, acrylic or methacrylic resins are preferably used in terms of heat resistance, additive dispersibility, productivity, and gloss. In terms of the light resistance of the resin layer, it is more preferable that the resin contains an ultraviolet absorber and a light stabilizer.

  Such ultraviolet absorbers and light stabilizers are roughly classified into inorganic and organic types, but are not particularly limited with respect to the form of inclusion, and may be a method such as mixing with a resin that forms such a resin layer. For example, when it is desired to prevent bleeding out from the resin layer, for example, a method of copolymerizing with a resin forming the resin layer may be used.

  As such inorganic ultraviolet absorbers, titanium oxide, zinc oxide, cerium oxide, etc. are generally known, and at least one selected from the group consisting of zinc oxide, titanium oxide and cerium oxide is 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 is most preferable from the viewpoints of economy, ultraviolet absorption, and photocatalytic activity. As such zinc oxide, FINEX-25LP, FINEX-50LP (manufactured by Sakai Chemical Industry Co., Ltd.) or the like can be used.

  Examples of such organic ultraviolet absorbers include benzotriazole and benzophenone. Since these ultraviolet absorbers only absorb ultraviolet rays and cannot capture organic radicals generated by ultraviolet irradiation, the white film of the base material may be chain-degraded by these radicals.

  In order to capture these radicals and the like, a light stabilizer is preferably used in combination, and a hindered amine (HALS) compound is preferably used as the light stabilizer.

  Here, as the copolymerization monomer for fixing the organic ultraviolet absorber and / or the light stabilizer, vinyl monomers such as acrylic and styrene are highly versatile and economically preferable. Among these copolymerizable monomers, since the styrene vinyl monomer has an aromatic ring and is easily yellowed, copolymerization with an acrylic vinyl monomer is most preferably used in terms of light resistance.

  As the benzotriazole substituted with a reactive vinyl monomer, 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole (trade name: RUVA-93); Otsuka Chemical ( In addition, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine (“Adeka Stab LA-82”) can be used in which a hindered amine compound is substituted with a reactive vinyl monomer. "; Manufactured by ADEKA Co., Ltd.) can be used.

  In the present invention, the organic ultraviolet absorber includes a resin containing an organic ultraviolet absorber such as benzotriazole or benzophenone, a resin copolymerized with a benzotriazole-based or benzophenone-based reactive monomer, or a hindered amine. A resin containing and / or copolymerizing a light stabilizer such as a (HALS) -based reactive monomer can be used within a range that does not impair the effects of the present invention.

  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 thin and have a high UV-absorbing effect. More preferred.

  These production methods and the like are disclosed in detail in JP-A-2002-90515 [0019] to [0039]. Among them, HALS HYBRID (registered trademark) (manufactured by Nippon Shokubai Co., Ltd.) containing an acrylic monomer and UV absorber copolymer as an active ingredient can be used.

  The content of the compound having at least one skeleton structure selected from skeleton structures (1) to (5) in the molecule in the resin layer according to the present invention is not particularly limited as long as the luminance can be improved. Since it depends on the type, dispersibility, productivity, etc. of this compound and nonporous spherical particles, it cannot be uniquely limited, but it is 0.2% by weight or more based on the entire resin layer containing this compound. More preferably, it is 1% by weight or more, more preferably 3% by weight, particularly preferably 10% by weight or more, and most preferably 30% by weight or more. The content of the compound may be selected so that the balance between the brightness enhancement effect and the change in chromaticity of the backlight light is good.

  When the content of the compound is less than 0.2% by weight, the brightness enhancement effect may not be obtained. The upper limit is not particularly limited, but if it exceeds 75% by weight, the productivity may be inferior or the chromaticity change of the backlight light may become extremely large. Therefore, the upper limit is controlled to 75% by weight or less. Is preferred.

  The thickness of the resin layer containing the compound having at least one skeletal structure selected from skeletal structures (1) to (5) and the nonporous spherical particles in the molecule according to the present invention is determined by the compound or nonporous structure. Since it also depends on the type and content of the spherical particles, it cannot be uniquely defined, but is preferably 0.05 to 50 μm or more, more preferably 1 to 15 μm, and particularly preferably 1 to 5 μm.

  When the thickness of the resin layer is less than 0.05 μm, the brightness enhancement effect may not be obtained or the light resistance may be insufficient. On the other hand, if the thickness exceeds 50 μm, the luminance may decrease or the chromaticity change of the backlight light may become extremely large, which is not preferable from the viewpoint of economy.

  In addition, the thickness of the resin layer here is a resin layer containing a compound having at least one skeleton structure selected from skeleton structures (1) to (5) in the molecule and nonporous spherical particles. It is the total thickness, and when it has one or more layers, it is the total thickness of each resin layer. However, when particles are included in the resin layer, the thickness of each layer is determined by selecting a location where no particles exist in the thickness direction.

  The nonporous spherical particles in the present invention cannot be uniquely limited because they depend on the type of the binder resin that forms the coating layer, but the difference in refractive index between the binder resin that forms the resin layer and the nonporous spherical particles. The absolute value (hereinafter referred to as refractive index difference) is preferably 0.30 or less. This refractive index difference is measured, for example, by the method described in Examples described later. If the refractive index difference is greater than 0.30, the light in the visible light region that contributes to the luminance of the light emitted from the lamp such as a cold cathode tube is reflected by the white film surface and transmitted through the resin layer. The light reaching the resin layer surface is reduced by excessive reflection and diffusion at the interface between the nonporous spherical particles and the binder resin. That is, the internal diffused light loss increases, and the reflectance is lowered without improving, and when the white reflective film of the present invention is incorporated in the backlight, the brightness improving effect may not be obtained. The difference in refractive index is preferably 0.3 or less, more preferably 0.1 or less, and particularly preferably 0.05 or less.

  The nonporous spherical particles in the present invention are not particularly limited because of the thickness of the resin layer and the content of the compound having a specific skeleton structure in the present invention in the molecule, but the average volume particle diameter is 0.05 μm or more. Preferably, it is 1 μm or more, more preferably 3 μm or more. That is, a convex structure may be formed on the outermost surface of the resin layer using particles having an average volume particle diameter larger than the thickness of the resin layer, and particles having an average volume particle diameter smaller than the thickness of the resin layer are used. Then, the surface of the resin layer may be as smooth as possible. When the average volume particle diameter is smaller than 0.05 μm, the backlight luminance improvement effect may not be obtained. Moreover, although an upper limit is not specifically limited, Since it may be inferior to workability when it exceeds 100 micrometers, 100 micrometers or less are preferable.

  The nonporous spherical particles in the present invention are not limited uniquely depending on the particle size of the particles, but the coefficient of variation CV is preferably 30% or less. Here, the “variation coefficient CV” is a value obtained by dividing the standard deviation of the volume particle diameter of the particles by the volume average particle diameter. “Particle volume particle diameter” means the diameter of a true sphere having the same volume as the particle, and “Volume average particle diameter” means the average value of the volume particle diameter of the corresponding particle group described above. It is. The coefficient of variation CV is an index of the uniformity of the volume particle diameter of the particles, and the value of the coefficient of variation CV decreases as the volume particle diameter is uniform. The coefficient of variation CV is measured by, for example, a Coulter counter method, a laser diffraction / scattering method, or dynamic light scattering. In the present invention, the coefficient of variation CV is measured by a method described in Examples described later. If the coefficient of variation CV is larger than 30%, the particle size is extremely large with respect to the thickness of the resin layer, and coarse particles that cause a defect defect from the resin layer, or the particle size is extremely small and refracted by light. In some cases, the resin layer contains a large amount of coarse and small particles having a poor brightness enhancement effect due to the small action of the angle change, which may deteriorate the quality of the white reflective film of the invention. The variation coefficient CV is more preferably 20% or less, further preferably 15% or less, and most preferably 10% or less.

  The content of the nonporous spherical particles in the present invention depends on the content of the compound contained together, the particle type, processability, etc., and thus cannot be uniquely limited. Although not limited, it is preferably 3% by weight or more, more preferably 5% by weight or more, further preferably 10% by weight or more, and particularly preferably 15% by weight with respect to the entire resin layer containing nonporous spherical particles. % Or more. When the amount is less than 3% by weight, the backlight luminance improvement effect may not be obtained. Moreover, although an upper limit is not specifically limited, When it is inferior to productivity when it exceeds 300 weight part with respect to 100 weight part of components other than the nonporous spherical particle in a resin layer, ie, 75 weight% of the whole resin layer. Therefore, 300 parts by weight, that is, 75% by weight or less of the entire resin layer is preferable with respect to 100 parts by weight of the components other than the nonporous spherical particles in the resin layer.

  Various additives can be added to the nonporous spherical particles in the present invention as long as the effects of the present invention are not impaired. Examples of additives include organic and / or inorganic fine particles, ultraviolet absorbers, light stabilizers, crosslinking agents, flame retardants, flame retardant aids, heat stabilizers, oxidation resistance stabilizers, organic lubricants, and antistatic agents. Agents, nucleating agents, dyes, fillers, dispersants, coupling agents, and the like can be used.

  The white film of the base material according to the present invention should have a high visible light reflectance, and for this purpose, a white film containing bubbles inside is preferably used. Although these white films are not limited, porous unstretched or biaxially stretched polypropylene films and porous unstretched or stretched polyethylene terephthalate films are preferably used as examples. About these manufacturing methods etc., [0034]-[0057] of JP-A-8-262208, [0007]-[0018] of JP-A-2002-90515, [0008]-[0034] of JP-A-2002-138150, etc. It is disclosed in detail. Among them, porous white biaxially stretched polyethylene terephthalate film disclosed in JP-A-2002-90515 and porous white biaxially stretched mixed and / or copolymerized with polyethylene naphthalate from the viewpoint of heat resistance and reflectivity A polyethylene terephthalate film is particularly preferred as the white film according to the present invention for the reasons described above.

  The structure of the white film of the base material according to the present invention may be appropriately selected depending on the intended use and required characteristics, and is not particularly limited, but is not limited to a single layer and / or 2 having a structure of at least one layer. A composite film having at least one layer is preferred, and at least one of the composite films preferably contains at least one of bubbles, inorganic particles, and organic particles.

  An example of a single layer configuration (= 1 layer) is, for example, a white film of a base material having only a single layer A, and the layer A contains at least one of bubbles, inorganic particles, and organic particles. The thing of composition is mentioned. Moreover, as an example of 2 layer structure, it is the white film of the base material of the 2 layer structure of A layer / B layer which laminated | stacked B layer on the said A layer, These A and B layers in at least any one layer , Bubbles, inorganic particles, and organic particles may be used. Furthermore, as an example of a three-layer structure, as described above, a white film of a base material having a three-layer laminated structure in which three layers of A layer / B layer / A layer and A layer / B layer / C layer are laminated. There is a configuration in which at least one of each layer contains at least one of bubbles, inorganic particles, and organic particles. In the case of a three-layer configuration, the B layer is most preferably a layer containing bubbles from the viewpoint of productivity.

  The number average particle diameter of the inorganic fine particles and / or organic particles contained in the white film of the base material is preferably 0.3 to 2.0 μm. As such organic particles, a resin mainly composed of a crosslinked polymer component having a high melting point is preferable. For example, polyester resin, polyamide resin particles such as benzoguanamine, polyurethane resin, acrylic resin, methacrylic resin, polyamide resin, polyethylene resin, Examples include polypropylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, fluorine-based resin, silicone resin particles, and hollow particles thereof. These resins may be used alone, or two or more copolymers or a mixture thereof may be used. In terms of the light resistance of the white film, it is preferable that the contained spherical particles contain an ultraviolet absorber and a light stabilizer. 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.

  As an example of such a substrate white film, first, as a white film having a single layer structure, Lumirror (registered trademark) E20 (manufactured by Toray Industries, Inc.), SY64, SY70 (manufactured by SKC), White Lefster (registered trademark) WS-220 (manufactured by Mitsui Chemicals Co., Ltd.) and the like, and as a white film having a two-layer structure, Tetron (registered trademark) film UXZ1, UXSP (manufactured by Teijin DuPont Films Co., Ltd.), PLP230 (Mitsubishi Resin Co., Ltd.) As a white film having a three-layer structure, Lumirror (registered trademark) E60L, E6SL, E6SR, E6SQ, E6Z (manufactured by Toray Industries, Inc.), Tetron (registered trademark) film UX (Teijin DuPont film) Etc.). Moreover, as an example of a white sheet having a configuration other than these, Optilon ACR3000, ACR3020 (manufactured by DuPont), MCPET (registered trademark) (manufactured by Furukawa Electric Co., Ltd.) can be mentioned.

  Various additives can be added to the white film and / or resin layer according to the present invention within a range that does not impair the effects of the present invention. Examples of additives include organic and / or inorganic fine particles, crosslinking agents, flame retardants, flame retardant aids, heat stabilizers, oxidation stabilizers, organic lubricants, antistatic agents, nucleating agents, dyes, and fillers. , Dispersants and coupling agents can be used.

  In the white reflective film of the present invention, the average reflectance at a wavelength of 400 to 700 nm measured from the surface provided with the resin layer is preferably 85% or more, more preferably 87% or more, and further preferably 90% or more. Most preferably, it is 95% or more.

  When the average reflectance is less than 85%, the luminance may be insufficient depending on the applied liquid crystal display. In addition, when the resin layer is provided in both surfaces, the average reflectance measured from any resin layer should just be 85% or more. As a method for setting the average reflectance at a wavelength of 400 to 700 nm to 85% or more, for example, there is a method of increasing the absolute amount of the light reflecting interface in the white film of the substrate or the resin surface. In particular, a method of forming more void structures in the white film of the base material described above or increasing the thickness of the portion having the void structure can be mentioned.

  In the present invention, the surface on which the resin layer is provided is not particularly limited, and has a two-layer structure of A layer / B layer, a three-layer structure of A layer / B layer / A layer or A layer / B layer / C layer. In some cases, it may be provided on either side.

  In the present invention, any method can be used for forming a resin layer containing a compound having at least one skeleton structure selected from skeleton structures (1) to (5) in the molecule on at least one surface of the white film. For example, a coating liquid containing a compound having at least one skeletal structure selected from Chemical Formula 1, Chemical Formula 2, Chemical Formula 3, Chemical Formula 4, and Chemical Formula 5 in the molecule is applied to a gravure coat, roll Using various coating methods such as coating, spin coating, reverse coating, bar coating, screen coating, blade coating, air knife coating, and dipping, it can be applied at the time of white film production of the substrate (in-line coating) or after completion of crystal orientation It can be formed by applying a coating layer on the white film (off-line coating), or a skeletal structure ( ) And a method of ~ the film or sheet containing a compound having a least one skeleton structure selected from (5) bonded by such lamination, but not particularly limited thereto.

  The white reflective film of the present invention thus obtained can improve the luminance of the liquid crystal backlight. Further, according to a preferred embodiment, the reflectance is little lowered even when used for a long time. Therefore, the white reflective film of the present invention can be suitably used as a reflector for an edge light type backlight for liquid crystal displays and a reflector for an edge light type or direct type backlight. In addition, it can be suitably used as a reflection plate for various surface light sources and a sealing film for solar cell modules that require reflection characteristics.

  The measurement method and evaluation method are shown below.

(1) Structure identification of compound When the structure of a compound is unknown, the following method is selected according to the form of the resin layer.

(I) Resin layer having no film such as a coating layer First, the resin layer of the sample is immersed in an organic solvent, and the resin layer is peeled and collected. Thereafter, the organic solvent after the resin layer is immersed is filtered. If there is filter cake, select a solvent having high solubility in the filter cake and dissolve it again. Next, a separable method is selected from general chromatography represented by silica gel column chromatography, gel permeation chromatography, liquid high-performance chromatography, gas chromatography, etc., and the filtrate and the redissolved filtrate solution are each simply used. Separate and purify into one substance. When it was difficult to separate by combining with other components in the resin layer, it was used as it was. Thereafter, each substance is appropriately concentrated and diluted, and nuclear magnetic resonance spectroscopy ( ¹ H-NMR, ¹³ C-NMR), two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR), infrared spectrophotometry (IR), Structure identification was performed by mass spectrometry (Mass) and elemental analysis.

(Ii) Resin layer by bonding or the like between films When bonding is performed, evaluation is performed separately for an adhesive resin layer and a resin layer film. First, the film that forms the resin layer is peeled off. Next, both the peeled white film of the substrate and the film forming the resin layer are immersed in an organic solvent, and the organic solvent after the resin adhesive layer is peeled and collected is filtered. If there is filter cake, select a solvent with high solubility in the filter cake and dissolve again.
Next, in the film forming the resin layer after the resin adhesive layer is peeled off, the organic solvent after being immersed in the organic solvent that dissolves the resin is filtered. When there is a filter as in the case of the resin adhesive layer, a solvent having a high solubility in the filter is selected and dissolved again. When it was difficult to separate by bonding with other components in the adhesive resin layer and the film forming the resin layer, it was used as it was. Each component is appropriately separated, purified, concentrated and diluted by the same method as in (i), followed by nuclear magnetic resonance spectroscopy ( ¹ H-NMR, ¹³ C-NMR), two-dimensional nuclear magnetic resonance spectroscopy (2D- NMR), infrared spectrophotometry (IR), mass spectrometry (MS), and elemental analysis were used for structural identification.

(2) Particle pore shape and particle shape in the resin layer The sample was cut in a direction perpendicular to the film plane at a knife inclination angle of 3 ° using a rotary microtome manufactured by Nippon Microtome Laboratories. Using the scanning electron microscope ABT-32 manufactured by Topcon Corporation, the obtained film cross section is, for example, at an observation magnification of 2500 to 10,000 times so that one particle is projected over the entire visual field region, and The image contrast was appropriately adjusted and observed, and the presence of pores and the shape of the particles were judged.
If the particles cannot be cut, the resin layer is immersed in an organic solvent, the coating layer is peeled and collected, and then the particles are removed from the resin layer by crimping and sliding on a slide glass to collect a sufficient amount of particles. . Subsequently, the obtained particles are used, for example, at an observation magnification of 2500 to 10,000 times so that one particle is projected over the entire visual field region using a scanning electron microscope ABT-32 manufactured by Topcon Corporation. Moreover, the contrast of the image was appropriately adjusted and observed, and the presence or absence of pores and the shape of the particles were judged.
Note that the presence / absence of pores is determined based on whether or not spots or spots are present in the particles in the observed image. There were no pores.

(3) Maximum absorption wavelength of compound in resin layer The compound was separated and purified by one of the same methods as in (1) and then dissolved in various soluble solvents. Next, this solution was put in a quartz cell, and an absorption spectrum at a wavelength of 200 to 900 nm was measured using an ultraviolet-visible spectrophotometer (UV-Bis Spectrophotometer, model V-660 manufactured by JASCO Corporation). The concentration is adjusted as appropriate within the range in which each maximum absorption wavelength can be observed. If the maximum absorption wavelength is between 300 and 450 nm, the concentration is acceptable, and if it is on the short wavelength side less than 300 nm, it is unacceptable and longer than the wavelength of 450 nm. The case where it exists in the wavelength side was set as the rejection 2.

(4) Emission wavelength of the compound in the resin layer The compound was separated and purified by any method similar to (1) and then dissolved in various soluble solvents. Next, this solution was put in a quartz cell, and using a spectrofluorometer (FP-6500 manufactured by JASCO Corporation), the maximum absorption wavelength obtained from (3) was irradiated as an excitation wavelength, An emission spectrum at a wavelength of 250 to 750 nm was measured. Concentration is adjusted so that the absorbance at the excitation wavelength is 1 when the optical path length is 1 cm. If the entire emission spectrum is between wavelengths 350-600 nm, pass 1; if it is between wavelengths 380-550 nm, pass 2. 2 is more preferable, when there is no light emission, or when a part of the emission spectrum is in the short wavelength region of less than 350 nm, fail A, and when part of the emission spectrum is in the longer wavelength region than wavelength 600 nm, reject B It was.

(5) Compound and particle content in resin layer The following method is selected according to the form of the resin layer.
(I) Resin layer not having a film such as a coating layer First, a sample is cut into a 30 cm square and the weight is measured. Next, the resin layer is immersed in an organic solvent, the weight of the sample after the resin layer is peeled and sampled is measured, the difference in the sample weight before and after the resin layer is peeled is calculated, and the value is the weight of the entire resin layer resin layer. And Further, each of the filtrate and the redissolved filtrate solution is separated and purified into a single substance by the same method as in (i) of (1). Isolates corresponding to the compounds and particles were concentrated and the total weight of each was measured. A value obtained by dividing the value of each total weight by the weight of the entire resin layer was obtained. Measurements were made at five locations in the same manner, and the average values at the five locations were defined as “compound content” and “particle content”.

(Ii) Resin layer by bonding or the like between films When bonding is performed, evaluation is performed separately for an adhesive resin layer and a resin layer film. First, by the same method as (ii) of (1), it is specified whether the compound is contained in one or both of the resin adhesive layer and the film forming the resin layer of the sample.
Next, after cutting the sample into 30 cm squares and measuring the weight, after peeling the film forming the resin layer, both the white film of the peeled substrate and the film forming the resin layer are immersed in an organic solvent, The weight of each of the white film of the material and the film forming the resin layer is measured. The weight of the resin adhesive layer is determined by subtracting the weight of the white film of the substrate and the film forming the resin layer from the total weight of the sample before peeling the resin layer. Furthermore, the same method as in (ii) of (1) separates and refines each component of the resin adhesive layer and each component of the film forming the resin layer into a single substance, and concentrates the separated substance corresponding to the compound and particles. Measure the total weight of each. A value obtained by dividing the value of each total weight by the sum of the weight of the film forming the resin layer and the weight of the resin adhesive layer was determined. At this time, if no compound is contained in either the film forming the resin layer or the resin adhesive layer, the weight is calculated as 0. Measurements were made at five locations in the same manner, and the average values at the five locations were defined as “compound content” and “particle content”.

(6) Thickness of resin layer First, the layer containing the compound of the sample is specified by the same method as in any one of (1). Next, the sample is cut in a direction perpendicular to the film plane at a knife inclination angle of 3 ° using a rotary microtome manufactured by Nippon Microtome Laboratory. The cross section of the obtained film is observed using a scanning electron microscope ABT-32 manufactured by Topcon Corporation, and only the binder resin or only the compound is contained in the resin layer laminated on the white film of the base material. The total thickness of the binder resin portion layer is measured at five locations on each side, and the average value is defined as the “resin layer thickness”.

(7) Refractive index difference between binder resin and particles in resin layer When the refractive index values of the binder resin and spherical particles were unknown, the difference was determined by the following procedure.
(I) After extracting the binder resin from the resin layer using an organic solvent, the filtrate and the redissolved filtrate solution are separated and purified into a single substance by the same method as in any of (1), and the binder resin is obtained. After purifying the purified product corresponding to (2) as appropriate, measurement is performed with respect to light having a wavelength of 589.3 nm at 25 ° C. by ellipsometry. This is carried out at five different places, and the average value of the five places is taken as the “refractive index of the binder resin” in this example.
(Ii) The resin layer of the white reflective film is immersed in an organic solvent, the resin layer is peeled off from the white film, and then the particles are dropped from the resin layer by pressing and sliding on a slide glass. The Becke line detection method is used to confirm that the particle outline is not visible at a temperature where the refractive index of each liquid organic compound is known, and the refractive index of the liquid organic compound used at this time is obtained. . This is carried out at five different locations, and the average value at the five locations is taken as the “particle refractive index” in this example.
(Iii) The difference between the refractive index value of the binder resin obtained from (i) and the refractive index value of the particles obtained from (ii) was obtained, and the value was defined as “the refractive index difference between the binder resin and the particles”. .

(8) Particle size distribution, volume particle diameter, average volume particle diameter, coefficient of variation CV of particles in the resin layer
First, the resin layer of the sample was immersed in an organic solvent, the resin layer was peeled and collected, and then the particles were removed from the resin layer by pressing and sliding on a slide glass, and washed appropriately with a solvent in which the particles did not dissolve . Using the Coulter Multisizer II (manufactured by Beckman Coulter, Inc.) as a particle size distribution measuring device using the pore electrical resistance method, the particles obtained here were converted into a particle volume when the particles passed through the pores. The number and volume of particles were measured by measuring the electrical resistance of the corresponding electrolyte solution. First, a small amount of sample is dispersed in a thin surfactant aqueous solution, and then added to the container of the specified electrolyte solution in such an amount that the aperture (detection portion pore) passage rate is 10 to 20% while viewing the monitor display. The particle size distribution of the particles was obtained by continuously measuring the volume particle diameter until the number of passing particles reached 100,000. Next, from the particles included in the volume particle diameter section from one end (volume particle diameter where the number of particles is 0%) to the other end (volume particle diameter where the number of particles is 0%) of the peak of the peak of the particle size distribution The average volume particle diameter, the standard deviation of the volume particle diameter, and the coefficient of variation CV were determined. The variation coefficient CV can be obtained by the following equation.
Coefficient of variation CV (%) = standard deviation of volume particle diameter (μm) / average volume particle diameter (μm) × 100.

(9) Light resistance (yellowness change Δb value)
A forced ultraviolet irradiation test was conducted under the following conditions using an ultraviolet deterioration accelerating tester iSuper UV Tester SUV-W131 (manufactured by Iwasaki Electric Co., Ltd.), and then the b value was determined. Three samples were subjected to an acceleration test, the b values before and after the test were measured, and the average value of the differences was defined as light resistance (yellowishness change Δb value).
"UV irradiation conditions"
Illuminance: 100 mW / cm ² , Temperature: 60 ° C., Relative humidity: 50% RH, Irradiation time: 48 hours Light resistance evaluation results are determined as follows. .
Class A: Yellowness change Δb value is less than 5
Class B: Yellowness change Δb value is 5 or more and less than 15
Class C: Yellowishness change Δb value is 15 or more.

(10) Average luminance, chromaticity change (Δx value, Δy value)
21 inch direct type backlight (using cold cathode tube, maximum emission wavelength of cold cathode tube at wavelength of 450 nm or less: 313 nm 365 nm 405 nm 436 nm, lamp tube diameter: 3 mmΦ, number of lamps: 12, distance between lamps: 25 mm, white reflective film And the distance between the lamp centers: 4.5 mm, and the distance between the diffusion plate and the lamp center: 13.5 mm), and the brightness and chromaticity were measured with the optical sheet configuration of the following two models.
Model 1: Diffusion plate RM803 (Sumitomo Chemical Co., Ltd., thickness 2 mm) / Diffusion sheet GM3 (Kimoto Co., Ltd., thickness 100 μm) 2 sheets Model 2: Diffusion plate RM803 (Sumitomo Chemical Co., Ltd., thickness 2 mm) / Diffusion sheet GM3 (manufactured by Kimoto Co., Ltd., thickness 100 μm) / prism sheet BEF-II (manufactured by 3M, thickness 130 μm) / polarized light separation sheet DBEF (manufactured by 3M, thickness 400 μm).

The measurement is performed by lighting the cold cathode ray tube for 60 minutes to stabilize the light source, and then using a color luminance meter BM-7fast (manufactured by Topcon Co., Ltd.) for luminance (cd / m ² ) and chromaticity (x value, y value). Was measured. For each value, an average value was calculated for three samples, and this was defined as average luminance and average chromaticity (x value, y value). Next, the difference between the obtained average chromaticity and the average chromaticity of the white film of the base material not provided with the resin layer was taken, and this was defined as chromaticity change (Δx value, Δy value).

Binder resins and compounds used in each Example and Reference Example are shown below.
Binder resin A: Acrylic resin (Foret GS-1000, 30% concentration solution manufactured by Soken Chemical Co., Ltd.)
Binder resin B: Benzotriazole-containing acrylic copolymer resin (manufactured by Nippon Shokubai Co., Ltd. Hals Hybrid (registered trademark) UV-G720T concentration 40% solution)
Compound A: Kyaphor SN (manufactured by Nippon Kayaku Co., Ltd., structural formula: structural formula (6) below (compound containing structural formula (1)))
Compound B: UVITEX OB (manufactured by Ciba Specialty Chemicals, Inc., structural formula: Structural formula (7) (compound including structural formula (2)))
Compound C: Shigenox 102 (manufactured by Hakkor Chemical Co., structural formula: structural formula (8) below (compound containing structural formula (3)))
Compound D: Hakkol PSR (manufactured by Hakkol Chemical Co., Ltd., structural formula: structural formula (9) below (compound containing structural formula (3)))
Compound E: 1,8-naphthalimide (manufactured by Tokyo Chemical Industry Co., Ltd., structural formula: structural formula (10) below (compound containing structural formula (4)))
Compound F: Anthracene (manufactured by Tokyo Chemical Industry Co., Ltd., structural formula: structural formula (11) below (compound containing structural formula (5)))
Compound G: Eastrite OB-1 (manufactured by Eastman Chemical Company, structural formula: Structural formula (12) below (compounds including structural formula (1) and structural formula (2)))
Compound H: Hostalux KS (manufactured by Clariant Japan Co., Ltd., structural formula: structural formula (13) below (compound containing structural formula (1) and structural formula (2)))
Compound I: Naphthalene (manufactured by Tokyo Chemical Industry Co., Ltd., Structural formula: Structural formula (14) below (compound not including any of the structural formulas (1) to (5)))
Compound J: Quinacridone (manufactured by Tokyo Chemical Industry Co., Ltd., structural formula: Structural formula (15) below (compound not including any structure of structural formula (1) to structural formula (5)))
Particle A: Nonporous spherical benzoguanamine / formaldehyde condensate particles (Epester (registered trademark) manufactured by Nippon Shokubai Co., Ltd., Epostor M05, refractive index 1.66, average volume particle size 5.2 μm, coefficient of variation CV 37%, polyamide Resin particles)
Particle B: Nonporous spherical acrylic particles (“TECHPOLYMER” MBX series, XX-09FP, refractive index 1.49, average volume particle size 5.0 μm, coefficient of variation CV 27%, manufactured by Sekisui Plastics Co., Ltd.) Polymer)
Particle C: Non-porous spherical silicon oxide (silica) particles (manufactured by Fuso Chemical Industry Co., Ltd. “Quartron” (registered trademark) SP series, SP-3C, refractive index 1.45, average volume particle diameter 3.0 μm, Coefficient of variation CV16%)
Particle D: Non-porous silicone particles (“TOSPEAR” (registered trademark) manufactured by GE Toshiba Silicone Co., Ltd., TOSPEARL 145, refractive index 1.42, average volume particle diameter 4.5 μm, coefficient of variation CV 12%)
Particle E: Non-porous acrylic particles (“TECHPOLYMER” (registered trademark) SSX series, SSX-105, manufactured by Sekisui Plastics Co., Ltd.), refractive index 1.49, average volume particle diameter 5.0 μm, coefficient of variation CV 9% , Acrylic copolymer)
Particle F: Porous spherical acrylic particles (“TECHPOLYMER” MBP series, MBP-4, refractive index 1.49, average volume particle diameter 4.0 μm, coefficient of variation CV 44%, acrylic co-polymer, manufactured by Sekisui Plastics Co., Ltd. Coalesce)
-Particle G: Non-porous amorphous aluminum hydroxide particles (Hijilite (registered trademark) H-32, manufactured by Showa Denko KK, refractive index 1.57, average volume particle diameter 8 μm, coefficient of variation CV 42%)

（実施例１）
バインダー樹脂Ａ：１０．００ｇ
トルエン：１０．１６ｇ
化合物Ａ：０．５６ｇ
粒子Ｅ：０．７３ｇ
を攪拌しながら添加して塗液を作った。
基材の白色フィルムとして多孔質の二軸延伸ポリエチレンテレフタレートで構成された３層構成の熱可塑性樹脂フィルム（東レ（株）製 ルミラー（登録商標）Ｅ６ＳＲ、厚み２２５μｍ）を準備した。前記塗液を、この基材白色フィルムの片面に、メタリングバー＃１３を使用して塗布し、１２０℃、１分間で加熱乾燥して、乾燥後の厚みが４．０μｍの樹脂層を設けて、本発明の白色反射フィルムを得た。

Example 1
Binder resin A: 10.00g
Toluene: 10.16 g
Compound A: 0.56 g
Particle E: 0.73 g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating liquid is applied to one side of the base white film using a metalling bar # 13, and heated and dried at 120 ° C. for 1 minute to provide a resin layer having a thickness of 4.0 μm after drying. Thus, a white reflective film of the present invention was obtained.

(Example 2)
Binder resin A: 10.00g
Toluene: 16.08 g
Compound A: 1.79 g
Particle E: 0.98 g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating liquid is applied to one side of the base white film using a metalling bar # 44, and heated and dried at 120 ° C. for 1 minute to provide a resin layer having a thickness of 13.0 μm after drying. Thus, a white reflective film of the present invention was obtained.

(Example 3)
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 1 except that the compound used was Compound B, and providing a resin layer having a thickness of 4.0 μm after drying.

Example 4
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 1 except that the compound used was Compound C, and providing a resin layer having a thickness of 4.0 μm after drying.

(Example 5)
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 1 except that the compound to be used was Compound D, and providing a resin layer having a thickness of 4.0 μm after drying.

(Example 6)
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 1 except that the compound to be used was Compound E, and providing a resin layer having a thickness of 4.0 μm after drying.

(Example 7)
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 1 except that the compound to be used was Compound F, and providing a resin layer having a thickness of 4.0 μm after drying.

(Example 8)
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 1 except that the compound to be used was Compound G, and providing a resin layer having a thickness of 4.0 μm after drying.

Example 9
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 1 except that the compound to be used was Compound H, and providing a resin layer having a thickness of 4.0 μm after drying.

(Example 10)
Binder resin B: 10.00g
Toluene: 16.84g
Compound G: 0.74 g
Particle E: 0.97 g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating liquid is applied to one side of the base white film using a metalling bar # 13, and heated and dried at 120 ° C. for 1 minute to provide a resin layer having a thickness of 4.0 μm after drying. Thus, a white reflective film of the present invention was obtained.

(Example 11)
Binder resin B: 10.00g
Toluene: 16.84g
Compound G: 0.74 g
Particle E: 0.97 g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating solution is applied to one side of the base white film using a metalling bar # 20, and heated and dried at 120 ° C. for 1 minute to provide a resin layer having a thickness of 6.0 μm after drying. Thus, a white reflective film of the present invention was obtained.

(Example 12)
Binder resin B: 10.00g
Toluene: 15.04 g
Compound G: 0.37 g
Particle E: 0.89g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating solution is applied to one side of the base white film using a metalling bar # 20, and heated and dried at 120 ° C. for 1 minute to provide a resin layer having a thickness of 6.0 μm after drying. Thus, a white reflective film of the present invention was obtained.

(Example 13)
Binder resin B: 10.00g
Toluene: 14.24g
Compound G: 0.20 g
Particle E: 0.86g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating liquid is applied to one side of the base white film using a metalling bar # 13, and heated and dried at 120 ° C. for 1 minute to provide a resin layer having a thickness of 4.0 μm after drying. Thus, a white reflective film of the present invention was obtained.

( Reference Example 14)
Binder resin B: 10.00g
Toluene: 257.5g
Compound G: 0.01 g
Particle E: 0.82g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating liquid is applied to one side of the base white film using a metalling bar # 3, and heated and dried at 120 ° C. for 1 minute to provide a resin layer with a thickness of 0.08 μm after drying. Thus, a white reflective film of the present invention was obtained.

(Example 15)
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 13 except that the particles used were changed to particles A, and providing a resin layer having a thickness of 4.0 μm after drying.

(Example 16)
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 13 except that the particles used were particles B, and providing a resin layer having a thickness of 4.0 μm after drying.

(Example 17)
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 13 except that the particles to be used were particles C, and providing a resin layer having a thickness of 4.0 μm after drying.

(Example 18)
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 13 except that the particles to be used were particles D, and providing a resin layer having a thickness of 4.0 μm after drying.

(Example 19)
Binder resin B: 10.00g
Toluene: 13.04 g
Compound G: 0.19 g
Particle E: 0.57 g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating liquid is applied to one side of the base white film using a metalling bar # 13, and heated and dried at 120 ° C. for 1 minute to provide a resin layer having a thickness of 4.0 μm after drying. Thus, a white reflective film of the present invention was obtained.

(Example 20)
Binder resin B: 10.00g
Toluene: 12.16 g
Compound G: 0.18 g
Particle E: 0.36 g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating liquid is applied to one side of the base white film using a metalling bar # 13, and heated and dried at 120 ° C. for 1 minute to provide a resin layer having a thickness of 4.0 μm after drying. Thus, a white reflective film of the present invention was obtained.

(Example 21)
Binder resin B: 10.00g
Toluene: 11.20 g
Compound G: 0.17 g
Particle E: 0.13 g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating liquid is applied to one side of the base white film using a metalling bar # 13, and heated and dried at 120 ° C. for 1 minute to provide a resin layer having a thickness of 4.0 μm after drying. Thus, a white reflective film of the present invention was obtained.

(Comparative Example 1)
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was used as a white reflective film without providing a resin layer.

(Comparative Example 2)
Binder resin B: 10.00g
Toluene: 10.00g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating solution is applied to one side of the base white film using a metalling bar # 13, and heated and dried at 120 ° C. for 1 minute to obtain a compound and particles having a thickness of 4.0 μm after drying. The white reflective film of this invention was obtained by providing the resin layer which does not contain.

(Comparative Example 3)
Binder resin A: 10.00g
Toluene: 6.80 g
Compound G: 0.45 g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating liquid is applied to one side of the base white film using a metalling bar # 13, dried by heating at 120 ° C. for 1 minute, and contains only a compound having a thickness of 4.0 μm after drying. A white reflective film of the present invention was obtained by providing a resin layer.

(Comparative Example 4)
Binder resin A: 10.00g
Toluene: 7.44g
Particle E: 0.61 g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating liquid is applied to one side of the base white film using a metalling bar # 13, dried by heating at 120 ° C. for 1 minute, and contains only particles having a thickness of 4.0 μm after drying. A white reflective film of the present invention was obtained by providing a resin layer.

(Comparative Example 5)
Except having used the compound I as the compound to be used, it produced similarly to Example 1, provided the resin layer whose thickness after drying is 4.0 micrometers, and obtained the white reflective film of this invention.

(Comparative Example 6)
A white reflective film of the present invention was obtained by preparing in the same manner as in Example 1 except that the compound to be used was Compound J, and providing a resin layer having a thickness of 4.0 μm after drying.

(Comparative Example 7)
A white reflective film of the present invention was obtained by preparing in the same manner as Example 13 except that the particles to be used were particles F, and providing a resin layer having a thickness after drying of 0.9 μm.

(Comparative Example 8)
Binder resin A: 10.00g
Toluene: 8.20 g
Compound G: 0.15 g
Particle G: 0.65g
Was added with stirring to make a coating solution.
A three-layer thermoplastic resin film (Lumirror (registered trademark) E6SR, manufactured by Toray Industries, Inc., thickness 225 μm) composed of porous biaxially stretched polyethylene terephthalate was prepared as a white film of the substrate. The coating liquid is applied to one side of the base white film using a metalling bar # 13, and heated and dried at 120 ° C. for 1 minute to provide a resin layer having a thickness of 4.0 μm after drying. Thus, a white reflective film of the present invention was obtained.

実施例１〜１３、１５〜２１のいずれにおいても、輝度向上効果が見られた。中でも化合物が構造式（１）及び構造式（２）の構造を有し、さらに無孔質球状粒子の変動係数ＣＶと樹脂層を形成するバインダー樹脂との屈折率差が特定の範囲にあり、且つ、樹脂層中に紫外線吸収剤および／または光安定化剤を含有したものは高い輝度向上効果を得られるだけでなく耐光性も付与できた（実施例１０）また、化合物や無孔質球状粒子の含有率、樹脂層厚みを変えることで輝度向上率や色度変化の調整が可能であった（実施例１１〜１３、１８〜２０）。

In any of Examples 1 to 13 and 15 to 21, a brightness improvement effect was observed. Among them, the compound has the structure of the structural formula (1) and the structural formula (2), and the refractive index difference between the coefficient of variation CV of the nonporous spherical particles and the binder resin forming the resin layer is in a specific range, In addition, the resin layer containing an ultraviolet absorber and / or a light stabilizer was able to provide not only a high brightness enhancement effect but also light resistance (Example 10). It was possible to adjust the luminance improvement rate and chromaticity change by changing the particle content and the resin layer thickness (Examples 11 to 13 and 18 to 20).

  When the compound has a structure of any one of structural formulas (1), (2), (3), (4), and (5) (Examples 1, 3, 4, 6, and 7), a brightness enhancement effect was confirmed. In the case where the compounds had the structures of the structural formulas (1) and (2) (Examples 8 and 9), the luminance improvement effect was particularly high although the chromaticity change was large. When the content of the compound in the resin layer was high and the resin layer was thick, the luminance improvement effect was higher although the chromaticity change increased in proportion thereto (Example 2). In any case where the compound has a structure of any one of structural formulas (1), (2), (3), (4), (5), or has a structure of structural formulas (1) and (2) Even when the substituents were bonded, the same brightness enhancement effect was obtained (Examples 5 and 9).

When the content of the compound in the resin layer is low and the thickness of the resin layer is thin ( Reference Example 14), although there is almost no change in chromaticity, even if nonporous spherical particles are contained, the brightness enhancement effect and light resistance are It became low.

  If the particles contained together with the compound having the structure of any one of the structural formulas (1), (2), (3), (4) and (5) are nonporous and spherical, the material (type of particles) ), A brightness improvement effect could be obtained irrespective of the coefficient of variation CV and the difference in refractive index from the binder resin forming the resin layer (Examples 15 to 18).

  When the resin layer was not provided (Comparative Example 1), the light resistance was unacceptable and the brightness enhancement effect was not obtained. Further, even when the resin layer is provided, only the compound is contained and no non-porous spherical particles are contained (Comparative Example 3), conversely, only the non-porous spherical particles are contained and no compound is contained (Comparative Example 4). Even if the particles are contained together with the compound, the particles are either spherical or porous (Comparative Example 7), and conversely, the particles are nonporous or non-spherical (Comparative Example 8). In some cases, the effect of improving luminance is poor, and even if a resin layer is provided, the compound having a structure of any one of structural formulas (1), (2), (3), (4), and (5) and a nonporous sphere In the case of not containing particles (Comparative Example 2), the brightness enhancement effect was not obtained. In addition, when the particles contained in the resin layer are porous (Comparative Example 7), the binder resin has an equivalent content and contains a light-resistant agent in the binder resin forming the resin layer. As a result, the resin layer thickness was extremely thin and the light resistance was inferior as compared with the case of being nonporous (Example 13).

  Even if the compound and nonporous spherical particles are added to the resin layer, the structure of the compound has any one of the structural formulas (1), (2), (3), (4), and (5). In the case where the maximum absorption wavelength is in the extremely short wavelength region and the light does not emit light, the luminance enhancement effect cannot be obtained (Comparative Example 5), and the maximum absorption wavelength and the light emission region are in the extremely long wavelength region. (Comparative Example 6) The light in the visible region emitted from the cold-cathode tube was absorbed and the luminance was lowered, and the chromaticity change was extremely increased.

It is an example of the cross-sectional schematic diagram of the white reflective film of this invention. It is an example of the cross-sectional schematic diagram of the white reflective film of this invention which contained the nonporous spherical particle in the resin layer. It is an example of the cross-sectional schematic diagram of the white film of the base material concerning this invention.

Explanation of symbols

1: White reflective film 2: Substrate white film having a three-layer structure 3: Resin layer containing compound 4: Coating layer containing compound 5: Adhesive layer containing compound 6: Resin film containing compound 7: Inorganic Particle and / or bubble-containing layer 8: Nonporous spherical particles larger than the coating layer thickness containing the compound 9: Nonporous spherical particles smaller than the coating layer thickness containing the compound 10: Adhesive layer thickness containing the compound Larger non-porous spherical particles 11: Smaller than non-porous spherical particles 12 smaller than the thickness of the adhesive layer containing the compound 12: Larger non-porous spherical particles 13 smaller than the thickness of the resin film containing the compound: Less than the thickness of the resin film containing the compound Nonporous spherical particles

Claims (9)

A compound having at least one skeleton structure selected from the group consisting of the following skeleton structures (1), (2), (3), (4) and (5) in the molecule on at least one surface of the white film. A white reflective film in which at least one resin layer containing 75% by weight and nonporous spherical particles is laminated.
Here, R _{1 to} R ₁₀ are unsubstituted or linear alkyl groups, branched alkyl groups, cyclic alkyl groups, alkenyl groups, aryl groups, aralkyl groups, alkoxy groups, sulfonic acid groups, acrylic groups, methacrylic groups, acryloxy groups, It represents a methacryloxy group, an oxycarbonyl group, an epoxy group, an isocyanate group, a substituted / unsubstituted amino group, a hydroxyl group, a carboxyl group, a halogen group, or a substituted / unsubstituted heterocycle .

  The white reflective film according to claim 1, wherein the compound has a structure of the skeleton structures (1) and (2) in the same molecule.   The white reflective film according to claim 1, wherein the compound has a maximum absorption wavelength between wavelengths of 300 to 450 nm.   The white reflective film according to claim 1, wherein the compound has a light emission between wavelengths of 350 to 600 nm.   The white reflective film in any one of Claims 1-4 which contains a ultraviolet absorber and / or a light stabilizer in the said resin layer.   A lamp reflector for a backlight, wherein the white reflective film according to claim 1 is provided with a surface on which the resin layer is laminated facing the light source.   6. An edge light type backlight comprising the white reflective film according to claim 1, the surface of which the resin layer is laminated facing the light guide plate.   A direct-type backlight comprising the white reflective film according to any one of claims 1 to 5 with a surface on which the resin layer is laminated facing the light source.   The film for solar cell sealing which used in order to seal a solar cell module, the white reflective film in any one of Claims 1-5.

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