JP2012212049A - Light reflection plate, light reflection product using the same, and display device and illumination device using these - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light reflection plate which has excellent strength, punching moldability and heat moldability.SOLUTION: In the light reflection plate which includes 100 pts.wt of an acyclic olefin resin, 10-180 pts.wt of a cyclic olefin resin, and 30-200 pts.wt of titanium oxide, the acyclic olefin resin used in the light reflection plate preferably uses a polypropylene resin, and particularly preferably uses polypropylene and an ethylene-propylene copolymer in combination.

Description

  The present invention relates to a light reflecting plate having excellent strength and excellent in punchability and thermoformability, a light reflecting molded body formed by molding the light reflecting plate, and a display device and an illumination device using the same. About.

  Liquid crystal display devices are used for various applications as display devices. In this liquid crystal display device, a backlight unit is disposed on the back surface of the liquid crystal cell. The backlight unit includes a light-emitting light source such as a cold cathode tube or an LED, a lamp reflector, a light guide plate, and a light reflection plate disposed on the rear surface side of the light guide plate. This light reflecting plate plays a role of reflecting light leaking to the rear surface side of the light guide plate toward the liquid crystal cell side.

  Along with the increase in the screen size of a display device or the like, an increase in the size of the light reflecting plate is also desired. However, when the light reflecting plate with low strength is enlarged, such a light reflecting plate is bent carelessly, and therefore there is a problem that handling property when the light reflecting plate is conveyed is low. Furthermore, inadvertent bending of the light reflector plate makes it difficult to dispose the light reflector plate at a desired position in the display device, resulting in a problem that the productivity of the display device is lowered. Therefore, the light reflecting plate needs to have excellent strength so as not to bend carelessly.

  As the light reflection plate, Example 11 of Patent Document 1 discloses an unstretched resin film containing a cyclic olefin-based resin and titanium oxide in a mass ratio of 60:40. In such an unstretched resin film, light reflectivity is obtained by utilizing light reflection caused by a difference in refractive index between the cyclic olefin resin and titanium oxide. Moreover, the unstretched resin film is ensuring the outstanding intensity | strength by containing cyclic olefin resin at 50 weight% or more and high concentration.

  As a light reflecting plate, Patent Document 1 discloses a porous resin film obtained by stretching a resin film containing a cyclic olefin-based resin and titanium oxide at least 1.1 times in a uniaxial direction. The porous resin film of Patent Document 1 has fine voids formed by starting with titanium oxide by stretching the resin film. And in the porous resin film of patent document 1, the refractive index of the light reflection produced by the refractive index difference of cyclic olefin resin and titanium oxide, and the void formed around cyclic olefin resin and titanium oxide. By utilizing the light reflection caused by the difference, excellent light reflectivity is obtained. In addition, the porous resin film also ensures excellent strength by including the cyclic olefin resin at a high concentration of 50% by weight or more.

  Furthermore, in the porous resin film of Patent Document 1, it is disclosed that, in addition to the inorganic filler, an insoluble resin incompatible with the cyclic olefin resin is finely dispersed in the cyclic olefin resin. . In patent document 1, polyolefin resin is mentioned as said insoluble resin. In Example 10 of Patent Document 1, a resin film containing a cyclic olefin resin, a polypropylene resin, a compatibilizing agent, and a rutile type titanium oxide at a weight ratio of 51: 7: 2: 40 is biaxially stretched. A porous resin film is disclosed.

  Such an insoluble resin is used to cause light reflection due to a difference in refractive index between the insoluble resin and the cyclic olefin-based resin to impart light reflectivity to the porous resin film. Therefore, the insoluble resin is used in a very small amount for the porous resin film, and hardly affects the mechanical properties of the porous resin film.

JP 2010-186152 A

  When the light reflection plate is incorporated in a display device or the like, the light reflection plate may be used as a light reflection molded body formed into a desired shape by punching and molding the light reflection plate. However, when the unstretched resin film or porous resin film of Cited Document 1 is formed into a desired shape by punching, the unstretched resin film and the porous resin film contain a high concentration of cyclic olefin resin. Due to the extremely high strength, there are many cases where molding defects such as cracks often occur, and there is a problem that the punching moldability is low.

  Further, when the light reflection plate is incorporated in a display device or the like, the light reflection plate may be used as a light reflection molded body formed into a three-dimensional shape by thermoforming the light reflection plate. However, the porous resin film of Patent Document 1 has deteriorated thermoformability due to excessive stretching treatment. When such a porous resin film is thermoformed, there is a problem in that the resulting molded body has a molding failure such as tearing or opening.

  Accordingly, an object of the present invention is to provide a light reflecting plate having excellent strength and excellent punching and thermoforming properties.

  The light reflecting plate of the present invention includes 100 parts by weight of an acyclic olefin resin, 10 to 180 parts by weight of a cyclic olefin resin, and 30 to 200 parts by weight of titanium oxide.

[Acyclic olefin resin]
In the present invention, the acyclic olefin resin means a chain olefin resin that does not have a ring structure formed of only carbon atoms in a repeating unit. The chain olefin resin includes an olefin resin having a linear structure and an olefin resin having a branched structure. Such an acyclic olefin-based resin is a polymer produced by polymerizing or copolymerizing an olefin that has only a carbon atom and does not have a ring structure. Preferred examples of the acyclic olefin resin include polyethylene resins and polypropylene resins. These acyclic olefin-based resins can be used alone or in combination of two or more.

  Examples of the polyethylene resin include low density polyethylene, linear low density polyethylene, high density polyethylene, and medium density polyethylene.

  Examples of the polypropylene resin include homopolypropylene, ethylene-propylene copolymer, propylene-α-olefin copolymer, and propylene-conjugated diene copolymer. The ethylene-propylene copolymer, propylene-α-olefin copolymer, and propylene-conjugated diene copolymer may be either a random copolymer or a block copolymer.

  The content of the ethylene component in the ethylene-propylene copolymer is preferably 0.5 to 30% by weight, and more preferably 1 to 10% by weight. In an ethylene-propylene copolymer having an ethylene component content of less than 0.5% by weight, the compatibility with the cyclic olefin-based resin may be reduced. Moreover, in the ethylene-propylene copolymer in which the content of the ethylene component exceeds 30% by weight, the strength and heat resistance of the obtained light reflecting plate may be reduced.

  The content of the α-olefin component in the propylene-α-olefin copolymer is preferably 0.5 to 30% by weight, and more preferably 1 to 10% by weight. Examples of the α-olefin include α-olefins having 4 to 10 carbon atoms, such as 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene and the like. Is mentioned.

  The content of the conjugated diene component in the propylene-conjugated diene copolymer is preferably 0.5 to 30% by weight, and more preferably 1 to 10% by weight. Examples of the conjugated diene include 1,3-butadiene, isoprene, 1,3-heptadiene, 2,3-dimethylbutadiene, and 2,5-dimethyl-2,4-hexadiene.

  Especially, it is preferable that the acyclic olefin resin contains a polypropylene resin. Provided is a light reflecting plate that has higher strength by using a polypropylene-based resin, and that can be molded into a desired shape while suppressing the occurrence of molding defects even when subjected to punching molding. be able to.

  As the light reflecting plate, the above-described polypropylene resin may be used alone, but it is preferable to use two or more kinds in combination, and more preferably includes a homopolypropylene and an ethylene-propylene copolymer. preferable. The ethylene-propylene copolymer has excellent compatibility with both the cyclic olefin resin and the homopolypropylene. Therefore, by using homopolypropylene and ethylene-propylene copolymer, homopolypropylene, ethylene-propylene copolymer, and cyclic olefin-based resin can be uniformly dispersed in the light reflector, and are used for punching molding. Thus, it is possible to provide a light reflection plate capable of suppressing the occurrence of molding defects to a higher level. In addition, by laminating a plurality of light reflecting plates to obtain a laminated body, and punching and molding the laminated body, productivity of the light reflecting plate can be improved. When stamping is performed, a higher pressure is applied to the light reflecting plate in the laminated body, so that molding defects such as cracks are particularly likely to occur in the light reflecting plate. However, in the light reflection plate using homopolypropylene and ethylene-propylene copolymer as the polypropylene-based resin, the occurrence of molding defects can be highly suppressed even if a plurality of these are laminated and punched.

  Furthermore, as described above, homopolypropylene, ethylene-propylene copolymer, and cyclic olefin resin are uniformly dispersed in the light reflecting plate containing homopolypropylene and ethylene-propylene copolymer as polypropylene resins. ing. Therefore, according to such a light reflection plate, even if it is thermoformed, the light reflection plate has a uniform thickness without producing a portion where the thickness is locally reduced, and the light reflection plate has excellent light reflectivity. It is also possible to provide a light reflection molded body molded into a desired shape while maintaining.

  The weight ratio of the homopolypropylene and the ethylene-propylene copolymer in the polypropylene resin is preferably 80:10 to 8:10, and more preferably 35:10 to 10:10. If the weight ratio of homopolypropylene in the polypropylene resin is too high, there is a possibility that the occurrence of molding defects cannot be sufficiently suppressed when the light reflecting plate is subjected to punching molding. Moreover, when the weight ratio of the homopolypropylene in the polypropylene resin is too low, the strength of the light reflecting plate may be lowered.

[Cyclic olefin resin]
In the present invention, the cyclic olefin resin means an olefin resin having a ring structure formed only of carbon atoms in a repeating unit. Such a cyclic olefin resin is a polymer produced by polymerizing or copolymerizing an olefin having a ring structure formed of only carbon atoms. Examples of the ring structure formed of only carbon atoms include cycloalkane structures derived from cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, and the like, and cyclopentene, cyclohexene, cycloheptene, cyclooctene, and cyclodecene. A cycloalkene structure derived from is preferable. In the cyclic olefin-based resin, a part of hydrogen may be substituted with a functional group such as a hydroxyl group, a carboxyl group, a nitrile group, an aryl group, and an alkoxysilyl group, or a halogen atom.

  The cyclic olefin-based resin is preferably obtained by polymerizing a monomer containing an olefin having a ring structure formed of only carbon atoms by a polymerization method such as metathesis ring-opening polymerization or addition polymerization. Synthesized by hydrogenating heavy bonds. Preferred examples of the olefin having a ring structure include cyclic olefins (also referred to as “cycloolefins”).

  Cyclic olefin resins include cyclic olefin addition (co) polymers or hydrogenated products thereof (1), cyclic olefin and α-olefin addition copolymers or hydrogenated products thereof (2), and Preferred are ring-opening (co) polymers of cyclic olefins or hydrogenated products (3) thereof.

Specific examples of the cyclic olefin include: cyclopentene, cyclohexene, cyclooctene; monocyclic olefin such as cyclopentadiene, 1,3-cyclohexadiene; bicyclo [2.2.1] hept-2-ene (common name) : Norbornene), 5-methyl-bicyclo [2.2.1] hept-2-ene, 5,5-dimethyl-bicyclo [2.2.1] hept-2-ene, 5-ethyl-bicyclo [2. 2.1] Hept-2-ene, 5-butyl-bicyclo [2.2.1] hept-2-ene, 5-ethylidene-bicyclo [2.2.1] hept-2-ene, 5-hexyl- Bicyclo [2.2.1] hept-2-ene, 5-octyl-bicyclo [2.2.1] hept-2-ene, 5-octadecyl-bicyclo [2.2.1] hept-2-ene, 5-methylidene Bicyclo [2.2.1] hept-2-ene, 5-vinyl-bicyclo [2.2.1] hept-2-ene, 5-propenyl-bicyclo [2.2.1] hept-2-ene, etc. A bicyclic olefin of tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene (common name: dicyclopentadiene), tricyclo [4.3.0.1 ^2,5 ] Deca-3-ene; tricyclo [4.4.0.1 ^2,5 ] undeca-3,7-diene or tricyclo [4.4.0.1 ^2,5 ] undeca-3,8-diene or these Tricyclo [4.4.0.1 ^2,5 ] undec-3-ene, a partially hydrogenated product (or adduct of cyclopentadiene and cyclohexene); 5-cyclopentyl-bicyclo [2.2.1] hepta-2 -Ene, 5-cyclohexyl-bicyclo [2.2.1] he A tricyclic olefin such as ta-2-ene, 5-cyclohexenylbicyclo [2.2.1] hept-2-ene, 5-phenyl-bicyclo [2.2.1] hept-2-ene; Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene (also simply referred to as tetracyclododecene), 8-methyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-ethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-methylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-ethylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-vinyltetracyclo [4,4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-propenyl-tetracyclo [4.4.0.1 ^2,5 . Tetracyclic olefins such as 1 ^7,10 ] dodec-3-ene; 8-cyclopentyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-cyclohexyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-cyclohexenyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene, 8-phenyl-cyclopentyl-tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene; tetracyclo [7.4.1 ^3,6 . 0 ^1,9 . 0 ^2,7 ] tetradeca-4,9,11,13-tetraene (also referred to as 1,4-methano-1,4,4a, 9a-tetrahydrofluorene), tetracyclo [8.4.1 ^4,7 . 0 ^1,10 . 0 ^3,8 ] pentadeca-5,10,12,14-tetraene (also referred to as 1,4-methano-1,4,4a, 5,10,10a-hexahydroanthracene); pentacyclo [6.6.1]. .1 ^3,6 . 0 ^2,7 . 0 ^9,14 ] -4-hexadecene, pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13] -4-pentadecene, pentacyclo [7.4.0.0 ^2,7. 1 ^3,6 . 1 ^10,13] -4-pentadecene; heptacyclo [8.7.0.1 ^2,9. 1 ^4,7 . 1 ^11,17 . 0 ^3,8 . 0 ^12,16 ] -5-eicosene, heptacyclo [8.7.0.1 ^2,9 . 0 ^3,8 . 1 ^4,7 . 0 ^12,17 . 1 ^13,16 ] -14-eicosene; and polycyclic cyclic olefins such as a tetramer of cyclopentadiene. These cyclic olefins can be used alone or in combination of two or more.

  Examples of the α-olefin copolymerizable with the cyclic olefin include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, and 3-ethyl. -1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene , 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and the like, preferably 2 to 20 carbon atoms ? -8 olefins. These α-olefins can be used alone or in combination of two or more.

  A commercial item can also be used as cyclic olefin resin. For example, “ZEONOR (registered trademark)” manufactured by Nippon Zeon Co., Ltd. (hydrogenated product of a ring-opening polymer of a cyclic olefin such as norbornene), “APEL (registered trademark)” manufactured by Mitsui Chemicals (tetracyclododecene and ethylene) Addition copolymer), and “TOPAS (registered trademark)” (addition copolymer of norbornene and ethylene) manufactured by Polyplastics.

  As the cyclic olefin-based resin, a hydrogenated product of a ring-opened polymer of a cyclic olefin, an addition copolymer of a cyclic olefin and an α-olefin, or a hydrogenated product thereof is preferably used. A hydrogenated product of a coalescence and an addition copolymer of norbornene and ethylene are more preferably used. By using these cyclic olefin-based resins, excellent strength can be imparted to the light reflecting plate.

  The glass transition temperature of the cyclic olefin-based resin is preferably 80 to 250 ° C, more preferably 100 to 200 ° C, and particularly preferably 100 to 170 ° C. If the glass transition temperature of the cyclic olefin-based resin is too low, the heat resistance of the obtained light reflector may be lowered. Moreover, if the glass transition temperature of the cyclic olefin resin is too high, the melt viscosity of the resin composition for forming a light reflecting plate, which will be described later, containing such a cyclic olefin resin increases, and the light reflecting plate is formed by extrusion molding. It may be difficult to manufacture, or the processing temperature when thermoforming the obtained light reflecting plate may be higher than necessary.

  The glass transition temperature of the cyclic olefin resin is a midpoint glass transition temperature (Tmg) defined by JIS K7121 (1987) when measured using a differential scanning calorimeter at a temperature rising rate of 10 ° C./min. ).

  The content of the cyclic olefin resin in the light reflecting plate is 10 to 180 parts by weight with respect to 100 parts by weight of the acyclic olefin resin, but is preferably 50 to 170 parts by weight, and more preferably 80 to 170 parts by weight. preferable. If the content of the cyclic olefin-based resin is less than 10 parts by weight, a light reflecting plate having sufficient strength may not be obtained. In addition, when the content of the cyclic olefin resin exceeds 180 parts by weight, the strength of the light reflecting plate becomes excessively higher than necessary, and when the light reflecting plate is stamped and molded, cracks and other molding defects are caused. There is a risk of it occurring.

  Further, the content of the cyclic olefin-based resin in the light reflecting plate is preferably 7 to 45% by weight with respect to the total amount of the light reflecting plate. If the content of the cyclic olefin-based resin is less than 7% by weight, a light reflecting plate having sufficient strength may not be obtained. In addition, when the content of the cyclic olefin resin exceeds 45% by weight, the strength of the light reflecting plate becomes excessively high, and when the light reflecting plate is punched and molded, the light reflecting plate has a molding defect such as a crack. There is a risk of it occurring.

  When an addition copolymer of cyclic olefin and α-olefin or a hydrogenated product thereof is used as the cyclic olefin resin, the content of the cyclic olefin resin in the light reflection plate is based on the total amount of the light reflection plate. 10 to 45% by weight is more preferable, 29 to 45% by weight is particularly preferable, and 36 to 40% by weight is most preferable. By making the content in the light reflector of the cyclic olefin resin consisting of an addition copolymer of cyclic olefin and α-olefin or a hydrogenated product thereof within the above range, heat resistance, thermoformability, punching A light reflecting plate that is particularly excellent in moldability, strength, and light reflectivity can be provided.

  When a hydrogenated product of norbornene ring-opening polymer is used as the cyclic olefin resin, the content of the cyclic olefin resin in the light reflection plate is 10 to 45% by weight with respect to the total amount of the light reflection plate. Is more preferable, 29 to 45% by weight is particularly preferable, and 30 to 36% by weight is most preferable. By making the content of the cyclic olefin resin comprising a hydrogenated ring-opening polymer of norbornene within the above-mentioned range, particularly in thermoformability, punching moldability, strength, and light reflectivity. An excellent light reflecting plate can be provided.

[Titanium oxide]
The light reflecting plate of the present invention is provided with excellent light reflectivity by containing titanium oxide. Titanium oxide is represented by the chemical formula TiO ₂ . Such titanium oxide includes rutile type, anatase type, and ilmenite type, but rutile type titanium oxide is preferable because of its excellent weather resistance.

Titanium oxide (TiO ₂ ) is preferably used as coated titanium oxide by coating its surface with a coating layer containing aluminum oxide and silicon oxide. By coating the surface of titanium oxide with a coating layer containing aluminum oxide and silicon oxide, it is possible to prevent direct contact between titanium oxide and acyclic olefin resin and cyclic olefin resin. Deterioration of the acyclic olefin resin and the cyclic olefin resin due to the photocatalytic action of titanium can be suppressed.

In the above coated titanium oxide, the amount of aluminum oxide converted to Al ₂ O ₃ determined by fluorescent X-ray analysis is preferably 1 to 6% by weight with respect to the total weight of titanium dioxide in the coated titanium oxide. -5 wt% is more preferred, and 1-4 wt% is particularly preferred.

In other words, in the above coated titanium oxide, the amount of aluminum oxide quantified by fluorescent X-ray analysis converted to Al ₂ O ₃ is when the total weight of titanium dioxide in the coated titanium oxide is 100% by weight. 1 to 6 wt% is preferable, 1 to 5 wt% is more preferable, and 1 to 4 wt% is particularly preferable.

  If the amount of aluminum oxide in the coating layer of the coated titanium oxide is too small, the suppression of the photocatalytic action of the titanium oxide is insufficient, resulting in coloration due to deterioration of the acyclic olefin resin, and the light reflecting performance of the light reflecting plate is lowered. There is a risk of doing. In addition, if the amount of aluminum oxide in the coating layer of the coated titanium oxide is too large, the coating layer absorbs visible light and the light reflection by the titanium oxide is reduced. As a result, the light reflecting performance of the light reflecting plate May decrease.

In the above coated titanium oxide, the amount of silicon oxide quantified by fluorescent X-ray analysis converted to SiO ₂ is preferably 0.1 to 7% by weight based on the total weight of titanium dioxide in the coated titanium oxide, 0.1 to 6% by weight is more preferable, and 0.1 to 5% by weight is particularly preferable.

In other words, in the above coated titanium oxide, the amount of silicon oxide quantified by fluorescent X-ray analysis converted to SiO ₂ is 0 when the total weight of titanium dioxide in the coated titanium oxide is 100% by weight. 0.1 to 7% by weight is preferable, 0.1 to 6% by weight is more preferable, and 0.1 to 5% by weight is particularly preferable.

  If the amount of silicon oxide in the coating layer of the coated titanium oxide is too small, the photocatalytic action of the titanium oxide is not sufficiently suppressed, and coloring due to deterioration of the acyclic olefin resin and the cyclic olefin resin occurs. There is a possibility that the light reflection performance of the lens will deteriorate. In addition, when the amount of silicon oxide in the coating layer of the coated titanium oxide is too large, the coating layer absorbs visible light, and the light reflection by the titanium oxide is reduced. As a result, the light reflecting performance of the light reflecting plate is reduced. There is a risk of lowering.

In the coating layer of the coated titanium oxide, the amount converted to Al ₂ O ₃ of the aluminum oxide quantified by fluorescent X-ray analysis, and converted to SiO ₂ of the silicon oxide quantified by fluorescent X-ray analysis The amount is measured using a fluorescent X-ray analyzer.

  In addition, in order to improve the dispersibility of the coated titanium oxide in the acyclic olefin-based resin, the surface of the coated titanium oxide is one or more coupling agents selected from the group consisting of a titanium coupling agent and a silane coupling agent. It is preferable to treat with a siloxane compound or a polyhydric alcohol, more preferably with a silane coupling agent.

  If the content of titanium oxide in the light reflecting plate is too small, the light reflecting performance of the light reflecting plate may be deteriorated. On the other hand, if the content of titanium oxide in the light reflector is too large, the light reflectivity of the light reflector cannot be improved in accordance with the increase in the titanium oxide content, and the lightness of the light reflector may be reduced. There is. Therefore, the content of titanium oxide in the light reflecting plate is limited to 30 to 200 parts by weight, preferably 50 to 200 parts by weight, and more preferably 50 to 195 parts by weight with respect to 100 parts by weight of the acyclic olefin resin. preferable.

[Antioxidant]
The light reflecting plate preferably further contains an antioxidant. By using the antioxidant, it is possible to provide a light reflecting plate capable of maintaining excellent light reflectivity over a long period of time. Preferable examples of the antioxidant include phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants.

  The light reflecting plate preferably contains a combination of a phenol-based antioxidant and a phosphorus-based antioxidant or a sulfur-based antioxidant. Thus, by using an antioxidant in combination, it is possible to provide a light reflecting plate that can maintain more excellent light reflectivity over a long period of time.

  Each content of the phenolic antioxidant, phosphorus antioxidant or sulfur antioxidant in the light reflector is 0.01 to 1.0 part by weight with respect to 100 parts by weight of the acyclic olefin resin. Is preferable, and 0.01 to 0.5 part by weight is more preferable.

[Ultraviolet absorber]
The light reflecting plate preferably further contains an ultraviolet absorber. By using the ultraviolet absorber, it is possible to provide a light reflecting plate capable of maintaining excellent light reflectivity over a long period of time.

  Preferred examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers. The benzotriazole ultraviolet absorber can effectively suppress a decrease in light reflectivity of the light reflector.

  The molecular weight of the ultraviolet absorber is preferably 250 or more, and more preferably 300 to 500. The UV absorber having a molecular weight of less than 250 volatilizes from the surface of the light reflecting plate when the light reflecting plate is thermoformed, and may cause defects such as uneven gloss, roughness, and tearing on the surface of the light reflecting molded body. There is. The light reflecting molded body in which these defects are generated cannot uniformly exhibit excellent light reflectivity.

  When there is too little content of the ultraviolet absorber in a light reflection board, there exists a possibility that the fall of the light reflectivity of a light reflection board cannot fully be suppressed. On the other hand, even if the content of the ultraviolet absorber in the light reflecting plate is too large, there is a possibility that the effect of suppressing the decrease in the light reflectance of the light reflecting plate does not change. Therefore, the content of the ultraviolet absorber in the light reflection plate is preferably 0.01 to 1.0 part by weight, more preferably 0.01 to 0.5 part by weight based on 100 parts by weight of the acyclic olefin resin. .

[Hindered amine light stabilizer]
It is preferable that the light reflection plate further contains a hindered amine light stabilizer. By using a hindered amine light stabilizer, it is possible to provide a light reflecting plate capable of maintaining excellent light reflectivity over a long period of time.

  If the content of the hindered amine light stabilizer in the light reflecting plate is too small, there is a possibility that a decrease in light reflectivity of the light reflecting plate cannot be suppressed. On the other hand, even if the content of the hindered amine light stabilizer in the light reflection plate is too large, there is no change in the effect of suppressing the decrease in light reflectivity of the light reflection plate, and the light reflection plate is colored by the hindered amine light stabilizer itself. There is a possibility that the light reflectivity of the film is lowered. Therefore, the content of the hindered amine light stabilizer in the light reflector is preferably 0.01 to 1.0 part by weight, and 0.01 to 0.5 part by weight with respect to 100 parts by weight of the acyclic olefin resin. Is more preferable.

  Further, the light reflector is made of a copper damage inhibitor (metal deactivator), an antistatic agent, a dispersant such as a metal stearate soap, a quencher, a lactone processing stabilizer, a fluorescent whitening agent, and a crystal nucleating agent. Other additives may be included.

[Light reflector]
The thickness of the light reflecting plate of the present invention is preferably 0.1 to 1.5 mm, more preferably 0.1 to 0.8 mm, and particularly preferably 0.1 to 0.6 mm. If the thickness of the light reflecting plate is too thin, the strength of the light reflecting plate may decrease, and the light reflecting plate may be bent. In addition, when the light reflecting plate is thermoformed and formed into an arbitrary shape, it is thin. There is a possibility that the portion is likely to be generated. On the other hand, if the thickness of the light reflecting plate is too thick, the thickness and weight of the device incorporating the light reflecting plate may increase.

The linear expansion coefficient of the light reflecting plate is preferably 20 × 10 ⁻⁵ [1 / ° C.] or less, and more preferably 15 × 10 ⁻⁵ [1 / ° C.] or less. A light reflector having a linear expansion coefficient exceeding 20 × 10 ⁻⁵ [1 / ° C.] may have low heat resistance. A light reflector having low heat resistance expands as the temperature inside the device rises when the temperature inside the device such as a display device or a lighting device in which the light reflector is disposed increases. There is a possibility that the surface of the light reflection plate is deformed into a wave shape or the like by coming into contact with the member. Thus, the light reflecting plate which deform | transformed will reduce light reflectivity.

  Next, the manufacturing method of the light reflecting plate of this invention is demonstrated. For the production of the light reflector of the present invention, other materials such as an acyclic olefin resin, a cyclic olefin resin, titanium oxide, and, if necessary, an antioxidant, an ultraviolet absorber and a hindered amine light stabilizer. A resin composition for forming a light reflecting plate containing an additive at a predetermined content is used. And the light reflecting plate which consists of a non-foamed sheet can be manufactured by shape | molding this resin composition for light reflecting plate formation in a sheet form.

  In order to improve the dispersibility of titanium oxide in the production of a light reflecting plate, a master batch containing an acyclic olefin resin and titanium oxide may be prepared in advance, and a light reflecting plate may be produced using the master batch. .

  And in order to shape | mold the resin composition for light reflecting plate formation in a sheet form, after melt-kneading the resin composition for light reflecting plate formation in an extruder, it extrudes by well-known methods, such as a T-die method and a calendar method. Extrusion from the extruder may be sufficient, and it is preferable to extrude from the extruder by the T-die method. In order to form the light reflecting plate-forming resin composition into a sheet by the T-die method, for example, a light reflecting plate-forming resin obtained by attaching a T die to the tip of an extruder and melt-kneading the T die in the extruder. What is necessary is just to carry out by extruding a composition in a sheet form.

  In the present invention, after the light reflecting plate forming resin composition is formed into a sheet shape to produce a light reflecting plate, no stretching treatment is performed to form fine voids starting from an inorganic filler such as titanium oxide. . Conventionally, after a resin composition for forming a light reflecting plate containing titanium oxide is formed into a sheet shape, a light reflecting plate having fine voids is manufactured by performing a stretching treatment. In order to impart sufficient light reflectivity to the light reflecting plate by such fine gaps, it is necessary to excessively stretch the resin composition for forming the light reflecting plate formed into a sheet shape, and the obtained light reflection The thermoformability of the plate is significantly reduced. Therefore, in the present invention, by manufacturing the light reflecting plate without performing the stretching treatment, it has excellent thermoformability and is thermoformed into a desired shape without causing molding defects such as tearing or opening. It is possible to obtain a light reflector that can be used.

  In addition, when a light reflecting plate is produced by extruding a resin composition for forming a light reflecting plate melted and kneaded in an extruder from a T die into a sheet shape, the light reflecting plate is wound at a winding speed slightly higher than the extrusion speed. Taken. Thus, winding up the light reflecting plate at a speed slightly higher than the extrusion speed is performed to prevent the light reflecting plate from slackening, and the light reflecting plate is not subjected to stretching treatment. Therefore, depending on the winding, fine voids are not generated from the inorganic filler in the obtained light reflecting plate.

  The void formed by starting from an inorganic filler such as titanium oxide by the stretching treatment usually has a diameter of 1 μm or more, particularly 3 μm or more. Even if a gap having a diameter of less than 1 μm is formed in the light reflector, such a gap is very little air mixed in the composition when the light reflector is formed, It does not affect the thermoformability and light reflectivity of the light reflector.

  Further, at least one surface of the light reflecting plate of the present invention may be subjected to a mirror finishing process. Preferably, after obtaining a sheet-like extrudate by extruding the light reflecting plate-forming resin composition from an extruder, before it is cooled and solidified to become a light reflecting plate, at least one of the sheet-like extrudates Mirror surface processing is performed on the surface. According to the mirror finish processing, it is possible to improve the surface smoothness of the sheet-like extrudate and provide a light reflecting plate having excellent light reflecting performance.

  As the mirror surface processing, for example, a sheet-like extrudate is supplied between a pair of rolls including a mirror roll whose outer peripheral surface is formed into a mirror surface and a support roll disposed to face the mirror roll. For example, a method of pressing a mirror roll on the surface of the extruded product is preferably used.

  The light reflecting plate of the present invention is suitably used for a display device or a lighting device. Since the light reflecting plate of the present invention has excellent light reflectivity, by using such a light reflecting plate for a display device or a lighting device, the displayed image is excellent in visibility, brightness reduction and unevenness. It is possible to provide a display device or a lighting device in which generation is suppressed.

  When the light reflector of the present invention is used in a display device, the light reflector of the present invention is suitable as a backlight unit for liquid crystal display devices such as word processors, personal computers, mobile phones, navigation systems, televisions, and portable televisions. Can be used.

  When the light reflecting plate of the present invention is used for a backlight unit of a liquid crystal display device, the light reflecting plate is incorporated in a direct light type backlight, a side light type backlight or a planar light source type backlight constituting the liquid crystal display device. Can be used.

  FIG. 1 shows a schematic diagram of a sidelight type backlight unit of a liquid crystal display device in which the light reflecting plate of the present invention is used. A liquid crystal display device shown in FIG. 1 includes a light reflecting plate 10, a light diffusion layer 20 laminated and integrated on the light reflecting plate 10, a light guide plate 30 disposed on the light diffusion layer 20, and a light guide plate 30. And a lamp reflector 50 for reflecting the light radiated from the light emitting light source 40 to the light guide plate 30. Examples of the light source 40 include a cooling cathode and an LED.

  The light diffusion layer 20 is formed by dispersing translucent particles 21 made of styrene resin or acrylic resin in a binder resin such as a thermoplastic resin. Further, the surface of the light diffusion layer 20 has an uneven shape formed by the translucent particles 21, and light can be diffused by the uneven shape.

  In the liquid crystal display device, light incident on the light guide plate 30 by the light emitting light source 40 is led out of the light guide plate 30 from the surface of the light guide plate 30 by repeatedly reflecting between the front and back surfaces of the light guide plate 30. Further, the light derived from the back surface of the light guide plate 30 is diffused so as to be uniform toward the front surface side of the light guide plate 30 by the uneven shape formed by the translucent particles 21 on the surface of the light diffusion layer 20. Reflected. Further, when light derived from the back surface of the light guide plate 30 passes through the light diffusion layer 20, the light is reflected by the light reflecting plate 10 toward the front surface side of the light guide plate 30. In this way, by combining the light guide plate 30, the light diffusion layer 20, and the light reflection plate 10 with the light emitting light source, the luminance of the liquid crystal display device can be improved and the luminance distribution in the surface direction of the liquid crystal display device can be made uniform. .

  In addition to the backlight unit of the above-described liquid crystal display device, the light reflector of the present invention is a backlight for a surface emitting system such as an illumination box, a slot lamp illuminator, a copier, and a projector type display. It can also be used by being incorporated in a lighting device constituting a facsimile, an electronic blackboard or the like. The illuminating device of this invention contains the said light reflection plate and a light source at least.

  The light reflecting plate of the present invention is used as a light reflecting molded body by forming it into a desired shape by thermoforming, punching or the like when it is used for various applications such as the display device and the lighting device described above. Is preferred.

  Even if the light reflecting plate of the present invention is thermoformed, it is highly possible to suppress the occurrence of molding defects such as tearing or perforation, and to a desired shape without deteriorating light reflectivity and appearance characteristics. It is possible to provide a molded light reflecting molded body.

  Examples of the thermoforming method of the light reflecting plate include vacuum forming and pressure forming. Examples of vacuum molding and pressure molding include plug molding, free drawing molding, plug and ridge molding, matched molding, straight molding, drape molding, reverse draw molding, air slip molding, plug assist molding, plug assist reverse. Examples include draw molding. In the thermoforming method, it is preferable to use a mold whose temperature can be adjusted. Further, the shape of the light reflection molded body may be determined according to the application for which the light reflection molded body is used, and is not particularly limited.

  In addition, although the light reflector of the present invention has excellent strength, there is no risk of forming defects such as cracks even if punching is performed. It is possible to provide a light reflection molded article having excellent appearance characteristics without reducing reflectivity.

  The light reflecting plate can be punched by using, for example, a method of punching a desired portion of the light reflecting plate with a Thomson knife or a punching die. At this time, a plurality of light reflecting plates may be laminated to form a laminated body, and the laminated body may be stamped and formed as described above. It is not necessary to heat the light reflecting plate when stamping the light reflecting plate, and even if punching is performed on the light reflecting plate at room temperature, the light reflecting plate is obtained without causing molding defects such as cracks. be able to.

  In the punching of the light reflecting plate, a light reflection plate in which a hole for inserting a light emitting light source such as an LED or a fixing tool such as a rivet is formed in the light reflecting plate by punching a desired portion of the light reflecting plate. A light-reflecting molded body that is molded into a desired shape by obtaining a molded body or punching the light-reflecting plate in accordance with the shape of the part where the light-reflecting plate is installed inside a device such as a lighting device or a display device. Can be obtained.

  Only one of thermoforming or punching may be performed on the light reflecting plate, or both thermoforming and punching may be performed. For example, it is possible to obtain a light-reflecting molded body formed into a desired shape by performing stamping and forming after thermoforming the light-reflecting plate.

  Hereinafter, an example of the light reflection molded article of the present invention and an illumination device using the same will be described with reference to FIGS.

  As shown in FIGS. 2 and 3, the light reflection molded body A is bulged by thermoforming the flat rectangular light reflection plate 10 from the front surface to the back surface in a portion excluding the outer periphery of the four sides. The plurality of inverted truncated quadrangular pyramid-shaped recesses 12, 12,... Are vertically and horizontally so that the opening edges of the recesses 12, 12 ... are parallel to the long side or the short side of the light reflecting plate 10. It is formed continuously.

  In addition, the inner bottom surface 13 of each of the recesses 12, 12... Has a planar square-shaped through hole 13a penetrating between the front and back surfaces by punching a part thereof, and the light source is transmitted through the through hole 13a. L is configured to be disposed. Further, the inner peripheral surface of the peripheral wall portion 14 of the recesses 12, 12... Is formed as a light reflecting surface that reflects light emitted from the light source.

  And the illuminating device using the said light reflection molded object is shown in FIG. As shown in FIG. 4, the illuminating device is configured such that an illuminating body C including a light reflection molded body A and a light emitting diode L is disposed in a housing 60. The casing 60 has a flat rectangular bottom surface 61 having a size slightly larger than the light reflection molded body A, and a rectangular frame-shaped peripheral wall extending upward from the four-side outer periphery of the bottom surface 61. Part 62. The upper end of the inner peripheral surface of the peripheral wall portion 62 is formed with a step portion 62a over the entire circumference, and the frosted glass or the optical sheet 80 is detachably disposed on the step portion 62a. Yes. The light source of the illuminator C may be a general-purpose light source in addition to the light emitting diode.

  A light source body 70 is prepared in which a large number of light emitting diodes L, L... Are arranged on a planar square substrate 71 having a size that can be laid on the bottom surface 61 of the housing 60. Note that, in a state where the light reflection molded body A is superimposed on the light source body 70, the through holes 13a of the respective recesses 12 and the positions of the respective light emitting diodes L of the light source body 70 are configured to coincide with each other.

  The light source body 70 is laid on the bottom surface portion 61 of the housing 60 with the light emitting diode L facing upward (in the opening direction of the housing 60). A is laid, and the light emitting diode L of the light source body 70 is disposed through the through-hole 13a of the concave portion 12 of the light reflection molded body A to constitute the illuminating body C.

  In using this lighting device B, first, a frosted glass or optical sheet 80 is detachably disposed on the stepped portion 62a of the peripheral wall portion 62 of the housing 60, and then the light emitting diode L is caused to emit light (FIG. 4). reference). Then, the light emitted radially from the light emitting diode L and incident on the inner peripheral surface of the concave portion 12 of the light reflecting molded body A is reflected once or a plurality of times on the inner peripheral surface, and the traveling direction is cloudy glass. Alternatively, the light is directed toward the optical sheet 80 and enters the frosted glass or the optical sheet 80. It is preferable that the light reflection molded body A of the illuminating body C and the frosted glass or the optical sheet 80 are not brought into close contact with each other.

  The optical sheet 80 contains a light diffusing agent such as titanium oxide that diffuses light therein, and the light incident in the optical sheet 80 is irregularly reflected by the light diffusing agent in the optical sheet 80, Alternatively, the light incident on the frosted glass is diffused by the frosted glass and further diffused and then emitted outward from the frosted glass or the optical sheet 80. Therefore, it is in a state of shining substantially uniformly.

  Here, the light incident on the frosted glass or the optical sheet 80 is irregularly reflected on the frosted glass or the optical sheet 80, and a part of the light is reflected in the direction of the light reflection molded body A, and again in the direction of the light reflection molded body A. Although incident, the light incident again in the light reflecting molded body A is reflected on the inner peripheral surface of the recess 12 and is incident again in the frosted glass or the optical sheet 80.

  Thus, the light emitted from the light emitting diode L is reflected toward the frosted glass or the optical sheet 80 while being diffused by being reflected on the inner peripheral surface of the concave portion 12, and thus the frosted glass or the optical sheet. Since 80 is irradiated with light with a substantially uniform light beam over the entire surface, the position of the light emitting diode is hardly seen through the frosted glass or the optical sheet 80.

  Then, the design or characters drawn directly on the frosted glass or optical sheet 80, or the design or characters drawn on the decorative sheet disposed on the frosted glass or optical sheet 80, is the frosted glass or optical sheet 80. The light is uniformly and uniformly emerged from the light emitted uniformly from the whole. Therefore, the lighting device described above can be suitably used as a lighting device for advertisements and billboards.

  The light reflecting plate of the present invention is made of an unstretched non-foamed sheet, does not have fine voids formed by stretching therein, and has excellent thermoformability. Therefore, by thermoforming the light reflecting plate, it is possible to provide a light reflecting molded body having a uniform thickness and a desired formation without causing molding defects such as tearing or perforation.

  Moreover, the light reflecting plate of the present invention is excellent in strength. Therefore, the light reflecting plate is excellent in handleability without being inadvertently bent during conveyance of the light reflecting plate, and is also disposed at a desired position when it is disposed inside a device such as a display device or a lighting device. And the productivity of the apparatus can be improved.

  Furthermore, although the light reflecting plate of the present invention has excellent strength, it does not cause molding defects such as cracks when punching. Therefore, the light reflecting molded body obtained by punching and molding the light reflecting plate of the present invention can highly suppress the occurrence of molding defects such as cracks on the surface, and has excellent light reflectivity and appearance characteristics. Yes. Further, when a long strip-shaped light reflecting plate is manufactured, even when the long strip-shaped light reflecting plate is rolled up, there is no appearance defect such as a crack in the light reflecting plate.

The schematic cross section of the backlight unit of the liquid crystal display device with which the light reflecting plate of this invention is used suitably. The perspective view of the light reflection molded object formed by thermoforming the light reflection board of this invention. The longitudinal cross-sectional view of the said light reflection molded object. The longitudinal cross-sectional view of the illuminating device using the said light reflection molded object. The figure for demonstrating the measuring method of the intensity | strength of a light reflection board. The perspective view of the molded object produced in evaluation of the thermoformability of a light reflection board.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

Example 1
A T-die mold was connected to the tip of a single screw extruder (caliber: 90 mm). Using this extruder, a light reflector was produced according to the following procedure. 55.6 parts by weight of homopolypropylene (PL500A manufactured by Sun Allomer, melt flow rate: 3.3 g / 10 min, density: 0.9 g / cm ³ ), ethylene-propylene random copolymer (PC540R manufactured by Sun Allomer, containing ethylene component) Amount: 8.6% by weight, melt flow rate: 5.0 g / 10 min 44.4 parts by weight, cyclic olefin resin 1 (addition copolymer of norbornene and ethylene, glass transition temperature: 138 ° C., polyplastic 18.5 parts by weight of TOPAS (registered trademark) 6013 manufactured by Susu Co., Ltd. 66.7 parts by weight of rutile type titanium oxide (average particle size 0.28 μm, CR-93 manufactured by Ishihara Sangyo Co., Ltd.), phenolic antioxidant (IRSFANOX (registered trademark) 1010 manufactured by BASF) 0.2 parts by weight, phosphorus antioxidant (IRGAFOS manufactured by BASF 68) 0.2 parts by weight, 0.2 parts by weight of a benzotriazole ultraviolet absorber (molecular weight 315.8, trade name TINUVIN (registered trademark) 326) manufactured by BASF, and a hindered amine light stabilizer (trade name manufactured by BASF) TINUVIN (registered trademark) 111) 0.2 parts by weight is supplied to a hopper of an extruder, melt kneaded at 230 ° C. to obtain a resin composition, and this die composition is attached to the tip of the extruder. By extruding from a die of a mold (sheet width 500 mm, slit gap 0.3 mm), a non-foamed light reflecting plate having a thickness of 0.4 mm was obtained.

(Examples 2 to 4)
As shown in Table 1, homopolypropylene, ethylene-propylene random copolymer, cyclic olefin resin 1, titanium oxide, phenolic antioxidant, phosphorus antioxidant, benzotriazole ultraviolet absorber, and hindered amine light A light reflector was obtained in the same manner as in Example 1 except that the amount of the stabilizer was changed.

(Example 5)
Instead of the ethylene-propylene random copolymer, ethylene-propylene block copolymer (BC6C, manufactured by Nippon Polypro Co., Ltd., ethylene component content: 3.0 wt%, melt flow rate: 2.5 g / 10 min) 44.4 Using parts by weight, as shown in Table 1, the amounts of cyclic olefin resin 1, titanium oxide, phenolic antioxidant, phosphorus antioxidant, benzotriazole ultraviolet absorber, and hindered amine light stabilizer A light reflecting plate was obtained in the same manner as in Example 1 except for the change.

(Example 6)
A T-die mold was connected to the tip of a single screw extruder (caliber: 90 mm). Using this extruder, a light reflector was produced according to the following procedure. 55.6 parts by weight of homopolypropylene (PL500A manufactured by Sun Allomer, melt flow rate: 3.3 g / 10 min, density: 0.9 g / cm ³ ), ethylene-propylene random copolymer (PC540R manufactured by Sun Allomer, containing ethylene component) Amount: 8.6 wt%, melt flow rate: 5.0 g / 10 min) 44.4 parts by weight, cyclic olefin resin 2 (hydrogenated product of norbornene ring-opening polymer, glass transition temperature: 105 ° C., 18.7 parts by weight of ZEONOR (registered trademark) 1020R manufactured by Nippon Zeon Co., Ltd., 67.2 parts by weight of rutile type titanium oxide (average particle size 0.28 μm, CR-93 manufactured by Ishihara Sangyo Co., Ltd.), phenolic antioxidant Agent (IRGANOX (registered trademark) 1010, manufactured by BASF) 0.2 parts by weight, phosphorus antioxidant (IRGAFOS16, manufactured by BASF) ) 0.2 parts by weight, 0.2 parts by weight of a benzotriazole ultraviolet absorber (molecular weight 315.8, trade name TINUVIN (registered trademark) 326) manufactured by BASF, and a hindered amine light stabilizer (trade name TINUVIN manufactured by BASF) (Registered Trademark) 111) 0.2 part by weight is supplied to a hopper of an extruder, melt-kneaded at 230 ° C. to obtain a resin composition, and the T-die mold in which this resin composition is attached to the tip of the extruder By extruding from a die having a sheet width of 500 mm and a slit gap of 0.3 mm, a non-foamed light reflecting plate having a thickness of 0.4 mm was obtained.

(Examples 7 to 8)
As shown in Table 1, homopolypropylene, ethylene-propylene random copolymer, cyclic olefin resin 1, titanium oxide, phenolic antioxidant, phosphorus antioxidant, benzotriazole ultraviolet absorber, and hindered amine light A light reflecting plate was obtained in the same manner as in Example 6 except that the blending amount of the stabilizer was changed.

Example 9
Instead of the ethylene-propylene random copolymer, ethylene-propylene block copolymer (BC6C, manufactured by Nippon Polypro Co., Ltd., ethylene component content: 3.0 wt%, melt flow rate: 2.5 g / 10 min) 44.4 Using parts by weight, as shown in Table 1, the amounts of cyclic olefin resin 2, titanium oxide, phenolic antioxidant, phosphorus antioxidant, benzotriazole ultraviolet absorber, and hindered amine light stabilizer A light reflecting plate was obtained in the same manner as in Example 6 except for the change.

(Comparative Example 1)
A T-die mold was connected to the tip of a single screw extruder (caliber: 90 mm). Using this extruder, a light reflector was produced according to the following procedure. Homopolypropylene (PL500A manufactured by Sun Allomer, melt flow rate: 3.3 g / 10 min, density: 0.9 g / cm ³ ) 100 parts by weight, rutile type titanium oxide (average particle size 0.28 μm, Ishihara Sangyo Co., Ltd.) CR-93) 56.3 parts by weight, phenolic antioxidant (IRGANOX (registered trademark) 1010 manufactured by BASF) 0.2 part by weight, phosphorus antioxidant (IRGAFOS168 manufactured by BASF) 0.2 part by weight, Benzotriazole-based ultraviolet absorber 1 (molecular weight 315.8, trade name TINUVIN (registered trademark) 326 manufactured by BASF) 0.2 part by weight, and hindered amine light stabilizer (trade name TINUVIN (registered trademark) 111 manufactured by BASF) 0.2 part by weight is supplied to a hopper of an extruder and melt kneaded at 230 ° C. to obtain a resin composition. T die tool attached objects on the tip of the extruder (sheet width 500 mm, slit clearance 0.3 mm) by extrusion from a nozzle of a thickness to obtain a light reflecting plate is and non-foamed and 0.4 mm.

(Comparative Example 2)
A T-die mold was connected to the tip of a single screw extruder (caliber: 90 mm). Using this extruder, a light reflector was produced according to the following procedure. 55.6 parts by weight of homopolypropylene (PL500A manufactured by Sun Allomer, melt flow rate: 3.3 g / 10 min, density: 0.9 g / cm ³ ), ethylene-propylene random copolymer (PC540R manufactured by Sun Allomer, containing ethylene component) Amount: 8.6% by weight, melt flow rate: 5.0 g / 10 min 44.4 parts by weight, cyclic olefin resin 1 (addition copolymer of norbornene and ethylene, glass transition temperature: 138 ° C., polyplastic 611.1 parts by weight of TOPAS (registered trademark) 6013) manufactured by Su Co., Ltd., 400 parts by weight of rutile type titanium oxide (average particle size 0.28 μm, CR-93 manufactured by Ishihara Sangyo Co., Ltd.), phenolic antioxidant (BASF) IRGANOX (registered trademark) 1010) 0.2 parts by weight, phosphorus antioxidant (IRGAFOS manufactured by BASF) 68) 0.2 parts by weight, 0.2 parts by weight of a benzotriazole ultraviolet absorber (molecular weight 315.8, trade name TINUVIN (registered trademark) 326) manufactured by BASF, and a hindered amine light stabilizer (trade name manufactured by BASF) TINUVIN (registered trademark) 111) 0.2 parts by weight is supplied to a hopper of an extruder, melt kneaded at 230 ° C. to obtain a resin composition, and this die composition is attached to the tip of the extruder. By extruding from a die of a mold (sheet width 500 mm, slit gap 0.3 mm), a non-foamed light reflecting plate having a thickness of 0.4 mm was obtained.

(Comparative Example 3)
Instead of the cyclic olefin resin 1, a cyclic olefin resin 2 (hydrogenated product of norbornene ring-opening polymer, glass transition temperature: 105 ° C., ZEONOR (registered trademark) 1020R manufactured by Nippon Zeon Co., Ltd.) was used. Obtained a light reflector in the same manner as in Comparative Example 2.

(Evaluation)
The light reflection plate was evaluated for linear expansion coefficient, strength, light reflectance, punching moldability, and thermoformability according to the following procedures. The results are shown in Table 1. In addition, the numerical value in the parenthesis in the column of the cyclic olefin resin in Table 1 indicates the content (% by weight) of the cyclic olefin resin with respect to the total amount of components contained in the light reflecting plate.

(Linear expansion coefficient)
The measurement of the linear expansion coefficient of the light reflecting plate was made by cutting the light reflecting plate into a flat rectangular shape having a length of 20 mm × width of 3 mm, and the coefficient of linear expansion (× 10 ⁻⁵ / ° C.) of the test piece. Was measured under the following conditions.

Measuring device: Thermomechanical measuring device (TMA / SS6200, manufactured by SII Nano Technology Co., Ltd.)
Temperature increase rate: 5 ° C / min Temperature range: 20-60 ° C
Measurement mode: Tensile test mode Load: 10 mN
Chuck spacing: 20mm Low load clip used

(Strength)
The intensity of the light reflecting plate was measured according to the following procedure according to JIS B7721.

  A test piece D was produced by cutting the light reflecting plate into a planar square shape having a side of 50 mm. Next, as shown in FIG. 5, one end of the test piece D was gripped with a width of 10 mm from one end to the other end using the clamp E so that the test piece D was in a horizontal state. Then, the load measuring meter F (Imada) is a portion of the upper surface of the test piece D that is 2 mm inside from the other end toward the one end and that is perpendicular to the protruding direction of the test piece D from the clamp E. Using a push-pull gauge (PSS) manufactured by Seisakusho, it was pressed by 10 mm vertically downward, the load (kgf) indicated by the load measuring instrument F was read in this state, and this load was used as the strength of the light reflector.

(Light reflectance)
The total light reflectivity (%) of the light reflector is the light reflectivity at a wavelength of 550 nm when the total reflection light is measured under an incident condition of 8 ° in accordance with measurement method B described in JIS K7105. It means a value measured in an environment of 20 ° C. and a relative humidity of 60%, and is a value expressed as a relative value when the light reflectance when a barium sulfate plate is used as a standard light reflecting plate is 100%. . In addition, 30 light reflection plates were prepared for the light reflectivity of the light reflection plate, and the arithmetic average value of the light reflectivity of each light reflection plate was used.

  Specifically, the light reflectance of the light reflector is determined by the ultraviolet-visible spectrophotometer commercially available from Shimadzu Corporation under the trade name “UV-2450”, and the trade name “ISR-2200” from Shimadzu Corporation. Can be measured in combination with an integrating sphere accessory device (inner diameter: φ60 mm) commercially available at

(Punching formability)
After preparing a test piece by cutting the light reflecting plate into a planar square shape with a side of 100 mm, and placing this test piece on a rubber mat (Cutter Mat CM-1890 for work table manufactured by Trusco Nakayama Co., Ltd.) The stamping formability of the light reflecting plate was evaluated by pressing the tip of a load measuring meter (manufactured by Imada Seisakusho, push-pull gauge PSS) with a load of 20 kgf and a load of 30 kgf for 5 seconds, respectively. In Table 1, “excellent”, “good” and “bad” are as follows.

Excellent: Even when the load measuring instrument was pressed against the test piece with each load of 30 kgf and 20 kgf, no crack occurred in the test piece.
Good: Cracks occurred in the light reflector when the load meter was pressed against the light reflector with a load of 30 kgf, but when the load meter was pressed against the light reflector with a load of 20 kgf, the crack was Did not occur.
Defect: When the load measuring instrument was pressed against the light reflecting plate with each load of 30 kgf and 20 kgf, the light reflecting plate cracked at both loads.

(Thermoformability)
The light reflecting plate is cut into a flat square shape with a side of 64 cm, heated for 3 seconds so that both sides become 150 ° C., and then the recess 15 is formed from the front side to the back side in the portion excluding the outer periphery of the four sides by match molding. After bulging and forming toward the side, the light reflecting molded body G shown in FIG. 6 was obtained by cutting from a predetermined location.

  The concave portion 15 of the light reflecting molded body G has a planar square bottom surface portion 16 having a side of 40 mm, and a peripheral wall extending so as to gradually spread outward from the four-side outer periphery of the bottom surface portion 16 toward the surface side. It consists of part 17. In the peripheral wall portion 17, four inverted isosceles trapezoidal peripheral wall pieces 17a, 17a,... Share the inclined sides facing each other over the entire length between the adjacent peripheral wall piece portions 17a, 17a. Accordingly, the bottom portion 16 is integrally connected in the circumferential direction to form a funnel shape. Further, the opening end of the peripheral wall portion 17 was formed in a planar square shape having a side of 47 mm, and the height from the inner surface of the bottom surface portion 16 to the surface of the light reflection molded body G was 40 mm.

And in the light reflection molded object G, the thickness of the center part of the bottom face part 16 and the thickness of the center part of four peripheral wall piece parts 17a, 17a ... are measured, respectively, and the thickness of the light reflection plate before thermoforming The ratio of the thickness (T) of each portion to (T ₀ ) ([%] = T [mm] / T ₀ [mm] × 100) was calculated to evaluate the thermoformability of the light reflecting plate. In Table 1, “excellent”, “good”, and “bad” are as follows.
Excellent: The ratio of the total thickness of the measurement part of the light reflection molded body G was 50% or more with respect to the thickness of the light reflection plate before thermoforming.
Good: The ratio of the total thickness of the measurement part of the light reflection molded body G was 30% or more and less than 50% with respect to the thickness of the light reflection plate before thermoforming.
Defect: The ratio of the total thickness of the measurement part of the light reflection molded body G to the thickness of the light reflection plate before thermoforming is less than 30%, or molding defects such as tearing or perforation in the light reflection molded body Produced.

  The light reflecting plate of the present invention is, for example, a backlight unit of a liquid crystal display device such as a word processor, a personal computer, a mobile phone, a navigation system, a television, and a portable television, and a backlight of a surface emitting system such as an illumination box. It can be used by being incorporated in an illuminating device constituting a light, a slot illuminator, a copying machine, a projector-type display, a facsimile, an electronic blackboard, or the like.

DESCRIPTION OF SYMBOLS 10 Light reflecting plate 12 Concave part 13 Inner bottom face of recessed part 13a Through-hole 14 Peripheral wall part 20 Light-diffusion layer 21 Translucent particle 30 Light guide plate 40 Light-emitting light source 50 Lamp reflector 60 Housing 61 Bottom part of casing 62 Surrounding wall part of casing 62a Step part of housing 70 Light source body 71 Substrate C Illuminator L Light emitting diode 51 Light reflector 52 Clamp 53 Load measuring meter

Claims (9)

  A light reflector comprising 100 parts by weight of an acyclic olefin resin, 10 to 180 parts by weight of a cyclic olefin resin, and 30 to 200 parts by weight of titanium oxide.   The light reflecting plate according to claim 1, wherein the acyclic olefin-based resin includes a polypropylene-based resin.   The light reflecting plate according to claim 1, wherein the acyclic olefin-based resin contains homopolypropylene and ethylene-propylene copolymer.   The light reflecting plate according to claim 1, wherein the thickness is 0.1 to 1.5 mm.   A light reflecting molded body obtained by molding the light reflecting plate according to claim 1.   A display device comprising the light reflecting plate according to claim 1.   A display device comprising the light reflecting molded body according to claim 5.   An illuminating device comprising the light reflecting plate according to claim 1.   An illumination device comprising the light reflecting molded body according to claim 5.

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