JP2013076738A - Method of manufacturing light reflecting compact, and mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a light reflecting compact having excellent light reflection performance and light diffusion performance.SOLUTION: In the method of manufacturing a light reflecting compact, which manufactures a light reflecting compact by thermoforming a light reflecting plate using a mold, a rugged part is formed on a forming surface of the mold, and the rugged part on the forming surface has a surface roughness Ra of 1 to 20 μm and an average spacing Sm of irregularities of 5 to 300 μm, and the light reflecting plate is pressed to the forming surface of the mold while being heated, to not only form the light reflecting plate along the forming surface of the mold but also transfer the rugged part on the forming surface of the mold to a surface of the reflecting plate, whereby a light reflecting compact which has a rugged surface having a surface roughness Ra of 1 to 20 μm and an average spacing Sm of irregularities of 5 to 300 μm is manufactured.

Description

  The present invention relates to a method for producing a light reflection molded article having excellent light reflection performance and light diffusion performance, and a mold used for producing this light reflection molded article.

  In recent years, liquid crystal display devices have been used for various purposes 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.

  As the light reflecting plate, a metal thin plate made of aluminum, stainless steel or the like, a film obtained by vapor-depositing silver on a polyethylene terephthalate film, a metal foil laminated with an aluminum foil, a porous resin sheet, or the like is used.

  Further, as a highly productive light reflecting plate, a light reflecting plate in which an inorganic filler such as barium sulfate, calcium carbonate, titanium oxide or the like is contained in a polypropylene resin is also used.

  As a light reflecting plate, Patent Document 1 includes a resin composition containing an aliphatic polyester resin or polyolefin resin and a fine powder filler, and the content ratio of the fine powder filler in the resin composition is 0.00. A reflective film comprising a layer that is greater than 1% by mass and less than 5% by mass as the outermost layer on the reflective surface is disclosed.

  However, in the paragraph [0114], the reflective film has a description that it is preferable to stretch the laminate at least 1.1 times in the uniaxial direction, but all the reflective films of the examples are biaxially stretched. The reflective film produced by biaxial stretching in this way is inferior in thermoformability, and in addition to the problem that it cannot be thermoformed into a desired shape, the light diffusibility is also insufficient. There is also a problem that there is.

Japanese Patent No. 4041160

  The present invention provides a method for producing a light reflection molded article having excellent light reflection performance and light diffusion performance and having a desired shape, and a mold used for production of the light reflection molded article.

  The method for producing a light reflecting molded body according to the present invention is a method for producing a light reflecting molded body, in which a light reflecting molded body is manufactured by thermoforming a light reflecting plate using a mold. Is formed with a surface roughness Ra of 1 to 20 [mu] m and an average interval Sm of 5 to 300 [mu] m, and the gold reflector is heated while heating the light reflecting plate. Molding is performed along the molding surface of the mold by pressing against the molding surface of the mold, and the unevenness portion of the molding surface of the mold is transferred to the surface of the light reflecting plate so that the surface roughness Ra is 1 to 20 μm. And the light reflection molded object which has an uneven surface whose average space | interval Sm of an unevenness | corrugation is 5-300 micrometers is characterized by the above-mentioned.

  The mold of the present invention is a mold used for thermoforming a light reflecting plate, and has an uneven portion formed on the molding surface of the mold, and the uneven portion has a surface roughness Ra. It is 1-20 micrometers, and the average space | interval Sm of an unevenness | corrugation is 5-300 micrometers.

  Since the method for producing a light reflecting molded body of the present invention has the above-described configuration, it has excellent light reflecting performance and light diffusing performance by thermoforming a light reflecting plate using a mold. In addition, a light reflection molded body having a desired shape can be easily manufactured.

  In the above method for producing a light reflection molded article, when the maximum height (Ry) of the irregularities on the molding surface of the mold is 5 to 80 μm, the light reflection molded article having more uniform light diffusion performance Can be manufactured.

  In the above method for producing a light reflection molded article, the light reflection plate is formed by coating 100 parts by weight of a polyolefin resin, and the surface of titanium oxide is coated with a coating layer containing aluminum oxide and silicon oxide, and the water content is 0. When containing 20 to 120 parts by weight of coated titanium oxide that is 5% by weight or less, the light reflecting plate contains the coated titanium oxide with excellent dispersibility in the polyolefin-based resin and is also included in the coated titanium oxide. The formation of bubbles due to the water content is highly suppressed, and the light reflection molded body manufactured using this light reflection plate has more uniform light reflection performance.

The schematic diagram of the backlight unit of the liquid crystal display device with which the light reflecting plate of this invention is used suitably. It is a perspective view of the light reflection board of the present invention thermoformed. It is a longitudinal cross-sectional view of the light reflecting plate of the present invention that is thermoformed. It is a longitudinal cross-sectional view of the illuminating device using the light-reflecting plate of this invention thermoformed. It is sectional drawing which showed an example of the metal mold | die. It is the model perspective view which showed the light reflection molded object obtained in the Example.

  In the method for producing a light reflection molded article of the present invention, a light reflection molded article is produced by thermoforming a light reflection plate using a mold.

  The light reflecting plate used in the method for producing a light reflecting molded body of the present invention is not particularly limited as long as it has light reflectivity and can be thermoformed. It is preferable that the light reflecting plate is formed from a thermoplastic resin sheet. The thermoplastic resin constituting the thermoplastic resin sheet is not particularly limited, and examples thereof include aliphatic polyester resins such as polyolefin resins and polylactic acid resins, and polyolefin resins are preferable.

  The polyolefin resin is not particularly limited, and examples thereof include a polyethylene resin and a polypropylene resin, and a polypropylene resin is preferable. In addition, polyolefin resin may be used independently or 2 or more types may be used together.

  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, and propylene-α-olefin copolymer. Further, when the light reflecting plate is foamed, the polypropylene resin is preferably a high melt tension polypropylene resin disclosed in Japanese Patent No. 2521388 or Japanese Patent Application Laid-Open No. 2001-226510. .

  In addition, the ethylene-propylene copolymer and the propylene-α-olefin 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. 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.

  Among these, as the polyolefin resin, a polypropylene resin is preferable, and homopolypropylene is particularly preferable. The coated titanium oxide can be particularly finely dispersed in the polypropylene resin.

  The light reflecting plate preferably contains an inorganic filler in order to improve light reflectivity. Examples of such inorganic fillers include, but are not limited to, titanium oxide, calcium carbonate, barium sulfate, magnesium carbonate, silica, styrene resin particles, acrylic resin particles, and the like. More preferably, the titanium surface is coated with a coating layer containing aluminum oxide and silicon oxide, and the titanium oxide surface is coated with a coating layer containing aluminum oxide and silicon oxide and has a water content. Particularly preferred is a coated titanium oxide having a N content of 0.5 wt% or less. Titanium oxide includes a rutile type, anatase type, and ilmenite type, but a rutile type is preferable because of excellent weather resistance.

  The coated titanium oxide formed by coating the surface of titanium oxide with a coating layer containing aluminum oxide and silicon oxide preferably has a water content of 0.5% by weight or less. Silicon oxide and aluminum oxide contained in the coating layer of the coated titanium oxide easily form a hydrate by adding with moisture, and various studies have been made that the coated titanium oxide contains a relatively large amount of moisture. It turned out from. Coated titanium oxide containing a large amount of moisture in this way has a large cohesive force between the coated titanium oxides, and is likely to cause aggregation, and fine dispersion in the light reflecting plate may be insufficient.

  Further, in order to produce a light reflecting plate having light reflectivity, when a resin composition containing a coated titanium oxide containing a large amount of moisture is extruded, the coated titanium oxide is heated by the resin composition being heated. In some cases, the moisture contained in the gasification vaporizes and bubbles are formed in the melt-kneaded resin composition. When bubbles are generated in the melt-kneaded resin composition, the coated titanium oxide present in the resin composition is moved to other parts in the resin composition due to the presence of the bubbles, and as a result, There is a possibility that the coated titanium oxide aggregates. Further, when bubbles in the resin composition are diffused to the outside when extruding the melt-kneaded resin composition, a large crater-shaped recess may be formed on the surface of the obtained light reflecting plate. is there. Such a crater-shaped recess may cause a decrease in light reflection performance or unevenness of the light reflecting plate.

  Furthermore, when bubbles are generated in the melt-kneaded resin composition, the bubbles are also included in the light reflection plate obtained by using the bubbles. Since the bubbles contained in the light reflecting plate have low light reflectivity, there is a possibility that the light incident on the light reflecting plate is transmitted through the light reflecting plate and led out from the back surface of the light reflecting plate. Therefore, the light reflecting plate containing bubbles may not be able to obtain excellent light reflecting performance, but may have uneven light reflectivity in the surface direction of the light reflecting plate.

  Therefore, the coated titanium oxide having a moisture content of 0.5% by weight or less is not only excellent in dispersibility, but also has a resin composition that is melt-kneaded at the time of extrusion molding because the amount of water contained therein is very small. The formation of bubbles due to the vaporization of moisture contained in the coated titanium oxide in the product can be suppressed to a high level, and the excellent dispersibility of the coated titanium oxide can be maintained in the resin composition. In addition, by suppressing the formation of bubbles, it is possible to suppress the formation of a large crater-shaped recess on the light reflecting plate surface.

  Therefore, the light reflecting plate containing the coated titanium oxide having a moisture content of 0.5% by weight or less is finely dispersed in the light reflecting plate with almost no aggregation of the coated titanium oxide. Bubbles are suppressed from being formed therein, and excellent light reflecting performance can be exhibited uniformly over the entire surface of the light reflecting plate.

  Thus, the moisture content of the coated titanium oxide is preferably 0.5% by weight or less, more preferably 0.01 to 0.5% by weight, and more preferably 0.01 to 0.45% by weight based on the total amount of the coated titanium oxide. % Is particularly preferred.

  In addition, the measurement of the moisture content of the coating titanium oxide contained in a light reflection board can be performed as follows. Components other than coated titanium oxide such as the thermoplastic resin used in the light reflector and the antioxidants, ultraviolet absorbers and light stabilizers described later are not water-absorbing and cannot contain water, and are included in the light reflector. Only the coated titanium oxide coating layer can contain water. Therefore, it can be considered that all the water contained in the light reflecting plate is contained in the coating layer of the coated titanium oxide. In addition, since the coated titanium oxide contained in the light reflecting plate is dispersed in the thermoplastic resin, the surface of the coated titanium oxide contained in the light reflecting plate is exposed without being coated with the thermoplastic resin. There is almost nothing, and the surface of the coated titanium oxide is coated with a thermoplastic resin that does not absorb water. Therefore, even if the light reflecting plate is left for a long time, the water content of the coated titanium oxide is kept constant without substantially changing.

From the above, in the present invention, first, the light reflector is cut into a predetermined size to obtain a test piece having a weight of 5 g, and the moisture content (W ₁ [g]) of the test piece is measured according to the following procedure. The water content of the test piece is regarded as the water content of the coated titanium oxide in the test piece. Then, the weight (W ₂ [g]) of the coated titanium oxide contained in the test piece is measured according to the following procedure, and the value calculated by the formula: 100 × W ₁ / (W ₁ + W ₂ ) is used as the test piece. The moisture content of the coated titanium oxide contained in [% by weight]. Then, at least 30 test pieces are prepared from the light reflecting plate, the water content of the coated titanium oxide is measured for each test piece, and the arithmetic average value is included in the water content of the coated titanium oxide contained in the light reflecting plate. Rate.

The moisture content of the test piece is measured by allowing the test piece to stand in an environment of a temperature of 25 ° C. and a relative humidity of 30% for one hour, and then evaporating the moisture contained in the test piece with a moisture vaporizer under the following conditions. The measured moisture content [g] is measured by a Karl Fischer moisture meter conforming to the chemical product moisture measurement method described in JIS K0068.
Apparatus: Moisture vaporizer (ADP-511, manufactured by Kyoto Electronics Industry Co., Ltd.)
MKC-510N manufactured by Kyoto Electronics Industry Co., Ltd.
Vaporization temperature: 230 ° C
Carrier gas: N ₂ 200 ml / min Moisture measurement time: 30 minutes

  In addition, the weight of the coated titanium oxide contained in the test piece was determined by baking the test piece at 550 ° C. for 1 hour using an electric furnace (for example, a muffle furnace STR-15K manufactured by Isuzu Co., Ltd.). Ash is obtained by ashing, and the weight [g] of the ash is measured with a measuring instrument (for example, an electronic balance HA-202M for high precision analysis manufactured by A & D Co., Ltd.). Is regarded as the weight of the coated titanium oxide contained in the test piece.

  The average particle size of the coated titanium oxide is preferably 0.10 to 0.35 μm, more preferably 0.15 to 0.35 μm, particularly preferably 0.15 to 0.30 μm, most preferably 0.20 to 0.30 μm. preferable. By using the coated titanium oxide having an average particle diameter within the above range, it is possible to provide a light reflecting plate capable of exhibiting excellent light reflecting performance uniformly in the surface direction of the light reflecting plate.

Further, by using the coated titanium oxide having a low water content, it is possible to suppress the aggregation of the coated titanium oxide highly and finely disperse the coated titanium oxide in the light reflecting plate. Specifically, the number of coated titanium oxide particles having a particle diameter of 0.10 to 0.39 μm in the light reflecting plate and not aggregated is 150 to 550 in the cross section along the thickness direction of the light reflecting plate. / 900 μm ² , particularly 200 to 500/900 μm ² .

  The average particle size and the particle size of the coated titanium oxide contained in the light reflecting plate are 0.10 to 0.39 μm, and the number of coated titanium oxides not aggregated can be measured as follows. it can.

  The average particle diameter of the coated titanium oxide can be measured as follows. First, for example, the light reflecting plate is cut over its entire length along the thickness direction, that is, the direction orthogonal to the surface. Next, from the SEM photograph obtained by photographing the cross section of the light reflecting plate with a scanning electron microscope (SEM) at a magnification of 10,000 times, the particle diameter of 100 or more coated titanium oxides was measured, The average particle diameter of the coated titanium oxide can be calculated by arithmetically averaging the obtained values.

  In the present invention, the particle diameter of the coated titanium oxide means the diameter of a perfect circle that is the smallest diameter that can surround the coated titanium oxide.

Further, the number of coated titanium oxides having a particle diameter of 0.10 to 0.39 μm contained in the light reflecting plate and not aggregated can be measured as follows. First, for example, the light reflecting plate is cut over its entire length along the thickness direction, that is, the direction orthogonal to the surface. Next, a cross section in the thickness direction of the light reflector is photographed with a scanning electron microscope (SEM) at a magnification of 2500 times or more, and a square-shaped measurement region with a side of 30 μm on the light reflector is selected from the SEM photograph. To do. Next, after measuring the particle diameter (μm) of the coated titanium oxide by observing each of the coated titanium oxides included in this measurement region with a magnification of 10,000 times or more by SEM, the above measurement is performed. Of the coated titanium oxide contained in the region, the coated titanium oxide having a particle diameter of 0.10 to 0.39 μm and not agglomerated is selected, and the number of coated titanium oxides (pieces / 900 μm ² ) is measured.

Then, the above measurement is performed in the same manner for at least 10 measurement regions selected so as not to overlap in the cross section of the light reflection plate, and the particle diameter included in each measurement region is 0.10 to 0.39 μm and is aggregated. The number of uncoated titanium oxides (pieces / 900 μm ² ) was measured, and the arithmetic average value thereof was determined as a coating having a particle diameter of 0.10 to 0.39 μm contained in the light reflector and not agglomerated. The number of titanium oxides (pieces / 900 μm ² ).

The coated titanium oxide is formed by coating the surface of titanium oxide (TiO ₂ ) with a coating layer containing aluminum oxide and silicon 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.

  Here, titanium oxide is a substance known as a catalyst having a strong redox power. In the coated titanium oxide containing a large amount of moisture, the moisture is radicalized into H · (H radical) and OH · (OH radical) by the strong reducing power of titanium oxide. Since the OH radical has a very strong oxidizing power, when the light reflector is used for a long period of time, the thermoplastic resin existing around the coated titanium oxide is oxidatively decomposed, phenolic antioxidants, etc. There is a risk of coloring due to deterioration of other additives. When the thermoplastic resin present around the coated titanium oxide is oxidatively decomposed, a gap is formed between the coated titanium oxide and the thermoplastic resin, and the coated titanium oxide present on the light reflecting plate surface is detached, and the light reflecting plate surface There is a possibility that a crater-like recess may be formed on the surface, or the light reflection performance may be lowered. Further, coloring due to deterioration of other additives also causes a reduction in the light reflection performance of the light reflector. In particular, in the case of using a liquid crystal display device such as a liquid crystal television, the temperature inside the device becomes as high as 40 to 60 ° C., which may promote the above-described oxidative decomposition of the thermoplastic resin and discoloration of other additives. There is.

  However, the coated titanium oxide having a moisture content of 0.5% by weight or less has a very small amount of water contained therein, so that the above-described oxidative decomposition of the thermoplastic resin and discoloration of other additives are highly suppressed. It becomes possible. Therefore, the light reflecting plate containing the coated titanium oxide having a water content of 0.5% by weight or less should maintain excellent light reflecting performance even when used for a long time in a high temperature environment. Is preferable.

  In addition, by covering 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 the thermoplastic resin, and thermoplasticity due to the photocatalytic action of titanium oxide. Deterioration of the resin can be suppressed. In addition, the coating layer of titanium oxide generally prevents ultraviolet light from entering the titanium oxide, and can prevent discoloration to dark gray due to oxygen defects due to photochemical changes in the titanium oxide crystal. The reflector hardly causes coloration due to the discoloration of titanium oxide during use, and the light reflector has excellent light reflection performance during use.

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, and coloring due to deterioration of the thermoplastic resin may occur, which may reduce the light reflecting performance of the light reflecting plate. There is. In addition, when 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 reflectance of the light reflecting plate is reduced. May decrease.

Further, in the above-mentioned coated titanium oxide, the amount of silicon oxide determined by fluorescent X-ray analysis converted to SiO ₂ is preferably 0.1 to 7% by weight with respect to 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 suppression of the photocatalytic action of the titanium oxide is insufficient, and coloring due to deterioration of the thermoplastic resin may occur, and the light reflecting performance of the light reflecting plate may be lowered. There is. 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.

  Specifically, for example, an X-ray tube (vertical Rh / Cr tube (3 / 2.4 kW)) using a fluorescent X-ray analyzer commercially available from Rigaku Corporation under the trade name “RIX-2100”, Analysis diameter (10 mmφ), slit (standard), spectral crystal (TAP (F to Mg) PET (Al, Si) Ge (P to Cl) LiF (K to U)), detector (F-PC (F to Ca) ) SC (Ti to U)) and measurement mode (bulk method, 10 m-Cr, no balance component).

  Specifically, a carbon double-sided pressure-sensitive adhesive tape is stuck on a carbon table, and a coated titanium oxide is stuck on the carbon double-sided pressure-sensitive adhesive tape. The amount of the coated titanium oxide is not particularly limited, but as a guideline, it is about 0.1 g, and the coated titanium oxide is evenly distributed in a virtual square frame with a side of 12 mm defined on the carbon double-sided adhesive tape. It is preferable that the carbon double-sided pressure-sensitive adhesive tape is covered with titanium oxide so that the carbon double-sided pressure-sensitive adhesive tape in the virtual frame portion is not visible.

Next, in order to prevent the coated titanium oxide from scattering, a polypropylene film is entirely covered with a carbon table to form a sample for X-ray measurement, and the above-mentioned X-ray measurement sample is used to measure the above-mentioned by a fluorescent X-ray analyzer. Under the measurement conditions, the amount of aluminum oxide in the coating layer of the coated titanium oxide converted to Al ₂ O ₃ and the amount of silicon oxide converted to SiO ₂ can be measured.

  The carbon base is made of carbon and may be a cylindrical shape having a diameter of 26 mm and a height of 7 mm. For example, the product name “Carbon Sample Base”, code number # 15/1046 from Oken Shoji Co., Ltd. It is commercially available. As the carbon double-sided pressure-sensitive adhesive tape, for example, a conductive carbon double-sided tape for SEM (12 mm width, 20 m roll) commercially available from Oken Shoji Co., Ltd. can be used. As the polypropylene film, for example, a polypropylene film having a thickness of 6 μm commercially available from Rigaku Denki Kogyo under the trade name “Cell Sheet Cat No. 3377P3” can be used.

  Next, the manufacturing method of the said coated titanium oxide is demonstrated. In order to produce coated titanium oxide, untreated titanium oxide is dispersed in water or a medium containing water as a main component to produce an aqueous slurry. The titanium oxide may be preliminarily pulverized using a wet pulverizer such as a vertical sand mill, a horizontal sand mill, or a ball mill in accordance with the degree of aggregation of the titanium oxide.

  At this time, it is preferable to set the pH of the aqueous slurry to 9 or more because titanium oxide can be stably dispersed in the aqueous slurry. Further, a dispersant may be added to the aqueous slurry. Examples of such a dispersant include phosphoric acid compounds such as sodium hexametaphosphate and sodium pyrophosphate, and silicate compounds such as sodium silicate and potassium silicate.

  Next, a coating layer containing aluminum oxide and silicon oxide is formed on the surface of titanium oxide. Specifically, either or both of a water-soluble aluminum salt and a water-soluble silicate are added to the aqueous slurry. Examples of the water-soluble aluminum salt include sodium aluminate, aluminum sulfate, aluminum nitrate, and aluminum chloride. Examples of the water-soluble silicate include sodium silicate and potassium silicate.

  Further, the neutralizing agent is added after or simultaneously with the addition of one or both of the water-soluble aluminum salt and the water-soluble silicate into the aqueous slurry. The neutralizing agent is not particularly limited, and examples thereof include acidic compounds such as inorganic acids such as sulfuric acid and hydrochloric acid, acetic acid and organic acids such as formic acid, hydroxides or carbonates of alkali metals or alkaline earth metals, and ammonium compounds. And basic compounds.

  As a method for forming a coating layer containing silicon oxide on the surface of titanium oxide, the methods described in JP-A Nos. 53-33228 and 58-84863 can be used. .

  In the manner described above, the surface of titanium oxide is entirely covered with one or both of aluminum oxide and silicon oxide, and then oxidized from the aqueous slurry using a known filtration device such as a rotary press or a filer press. Titanium is filtered and separated, and if necessary, the titanium oxide is washed to remove soluble salts.

  When a water-soluble aluminum salt and a water-soluble silicate are added to the aqueous slurry, the coated titanium oxide whose surface is coated with a coating layer containing aluminum oxide and silicon oxide is added as described above. Can be obtained.

  On the other hand, when only one of the water-soluble aluminum salt and the water-soluble silicate is added to the aqueous slurry, the titanium oxide coated with either the water-soluble aluminum salt or the water-soluble silicate is not used. The aqueous slurry is prepared in the same manner as described above, and the other salt of the water-soluble aluminum salt or the water-soluble silicate is added to the aqueous slurry in the same manner as described above. Is coated with a water-soluble aluminum salt or the other salt of a water-soluble silicate, and a coated titanium oxide in which the surface of titanium oxide is coated with a coating layer containing aluminum oxide and silicon oxide can be obtained. .

  When the moisture content of the coated titanium oxide is 0.5% by weight or less, the coated titanium oxide used for manufacturing the light reflector is heated to evaporate the hydrated water contained in the coated titanium oxide. It can be carried out. Thus, it is preferable to use the coated titanium oxide having a moisture content of 0.5% by weight or less by heating and drying in advance for the production of the light reflecting plate.

  In order to remove or reduce hydration water contained in the coated titanium oxide, the hydrated water is evaporated by heating the coated titanium oxide preferably at 50 to 140 ° C, more preferably 90 to 120 ° C. Is preferably removed or reduced. The heating time is preferably 2 to 8 hours, and more preferably 3 to 5 hours.

  In addition, depending on the degree of aggregation of titanium oxide coated with either water-soluble aluminum salt or water-soluble silicate, hammer mill, impact mill such as pin mill, grinding mill such as crusher, It is preferable to pulverize using an air-flow pulverizer such as a jet mill, a spray dryer such as a spray dryer, a wet pulverizer such as a vertical sand mill, a horizontal sand mill, or a ball mill, and an impact pulverizer or a grinding pulverizer is preferable. .

  If the content of the coated 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 the coated titanium oxide in the light reflecting plate is too large, the light reflecting performance of the light reflecting plate is not expected to improve in accordance with the increase in the content of the coated titanium oxide, and the light weight of the light reflecting plate is reduced. There is a risk of doing. Therefore, the content of the coated titanium oxide in the light reflecting plate is preferably 20 to 120 parts by weight, more preferably 30 to 120 parts by weight, and particularly preferably 30 to 100 parts by weight with respect to 100 parts by weight of the thermoplastic resin.

  In order to improve the dispersibility of the coated titanium oxide in the thermoplastic 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, and a siloxane compound. It is preferable to treat with a polyhydric alcohol, and it is more preferred to treat with a silane coupling agent.

  Examples of the silane coupling agent include alkoxysilanes having an alkyl group, alkenyl group, amino group, aryl group, epoxy group, chlorosilanes, polyalkoxyalkylsiloxanes, and the like. Specifically, examples of the silane coupling agent include n-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, n-β (aminoethyl) γ-aminopropylmethyltrimethoxysilane, and n-β (amino Ethyl) aminosilane coupling agents such as γ-aminopropylmethyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, n-phenyl-γ-aminopropyltrimethoxysilane, dimethyldimethoxysilane, methyl Trimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, n-butylmethyldimethoxysilane, n-butylmethyldiethoxysilane, isobutyltrimethoxysilane, Examples of the alkylsilane coupling agent include butyltriethoxysilane, isobutylmethyldimethoxysilane, tert-butyltrimethoxysilane, tert-butyltriethoxysilane, tert-butylmethyldimethoxysilane, and tert-butylmethyldiethoxysilane. An aminosilane coupling agent is preferred. In addition, a silane coupling agent may be used independently or 2 or more types may be used together.

  Examples of the siloxane compound include dimethyl silicone, methyl hydrogen silicone, and alkyl-modified silicone. Examples of the polyhydric alcohol include trimethylol ethane, trimethylol propane, tripropanol ethane, pentaerythritol, pentaerythritol and the like, and trimethylol ethane and trimethylol propane are preferable. In addition, a siloxane compound and a polyhydric alcohol may be used independently, or 2 or more types may be used together.

  The above-mentioned coated titanium oxide is EIDupont de Nemours & Co., SCM Corporation, Kerr-McGee Co., Canadean Titanium Pigments Ltd., Tioxide of Canada Ltd., Pigmentos y Productos Quimicos, SAde CV, Tibras Titanos SA, Tioxide International Ltd. ., SCM Corp., Kronos Titan GmbH, NL Chemical SA / NV, Tioxide, TDF Tiofine BV, Ishihara Sangyosha, Teika, Sakai Chemical Industry, Furukawa Machine Metal, Tochem Products, Titanium Industry, Fuji Titanium Industry , Korea Titanium Co., China Metal Processing Co., ISK Taiwan Co., Ltd. and others.

  The light reflection plate may contain a primary antioxidant. This primary antioxidant is a stabilizer that traps radicals generated by heat or light and stops the radical reaction, and as such a primary antioxidant, it suppresses a decrease in light reflectance of the light reflector. A phenolic antioxidant is preferred because of its high effect.

  Examples of the phenolic antioxidant include 2,6-di-t-butyl-4-methylphenol and n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl). ) Propionate, tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxymethyl] methane, tris [N- (3,5-di-t-butyl-4-hydroxybenzyl)] Isocyanurate, butylidene-1,1-bis (2-methyl-4-hydroxy-5-t-butylphenyl), triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) Propionate], 3,9-bis {2- [3 (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4 8,10-tetraoxaspiro [5.5] undecane and the like, may be also alone, or two or more are used alone.

  And, if the content of the primary antioxidant in the light reflecting plate is small, it may not be possible to suppress a decrease in the light reflectivity of the light reflecting plate, while at most, the light reflectivity of the light reflecting plate. There is no change in the effect of suppressing the decrease in the amount of light, and the light reflectance of the light reflecting plate may decrease due to the coloring of the primary antioxidant itself, so 0.01 to 0.5 weight with respect to 100 parts by weight of the thermoplastic resin Part is preferable, 0.01 to 0.3 part by weight is more preferable, and 0.01 to 0.2 part by weight is particularly preferable.

  Here, if the coated titanium oxide contains a large amount of moisture, the light reflecting plate is heated during thermoforming of the light reflecting plate, thereby generating a strong reducing power of titanium oxide and being included in the coated titanium oxide. Much water is radicalized into H. and OH. The OH radicals generated by this attack the phenolic antioxidant contained in the light reflector and form a colored substance such as stilbenginone (brown), causing the light reflector to turn yellow. May also occur. However, according to the coated titanium oxide having a moisture content of 0.5% by weight or less, even if the light reflecting plate contains a phenolic antioxidant, the amount of water in the light reflecting plate is small. A coloring substance hardly occurs due to the attack of the phenolic antioxidant, and the discoloration of the light reflecting plate can be highly suppressed, which is preferable.

  In addition, the light reflection plate may contain a secondary antioxidant. This secondary antioxidant inhibits auto-oxidation by ionic decomposition of hydroperoxide (ROOH), which is an intermediate of auto-oxidative degradation of thermoplastic resins caused by heat and light. Phosphorous antioxidants and sulfur-based antioxidants are preferable, and phosphorus-based antioxidants are more preferable because they have a high effect of suppressing a decrease in light reflectance of the light reflecting plate.

  Examples of the phosphorus antioxidant include tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, and bis (2,4-diphenyl). -T-butylphenyl) pentaerythritol phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) -4,4'-biphenylenedi-phosphonite, and the like. Two or more kinds may be used in combination.

  Examples of the sulfur-based antioxidant include dilauryl-3,3′-thio-dipropionate, dimyristyl-3,3′-thio-dipropionate, distearyl-3,3′-thio-dipropionate, pentaerythritol tetrakis. (3-laurylthio-propionate) and the like may be mentioned, and these may be used alone or in combination of two or more.

  When there is too little content of the secondary antioxidant in a light reflection board, the fall of the light reflectivity of a light reflection board may be unable to be suppressed. On the other hand, even if the content of the secondary antioxidant 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 secondary antioxidant in the light reflector is preferably 0.01 to 0.5 parts by weight, and 0.01 to 0.3 parts by weight with respect to 100 parts by weight of the thermoplastic resin. Is more preferable, and 0.01 to 0.2 part by weight is particularly preferable.

  Furthermore, the light reflecting plate may contain an ultraviolet absorber. Examples of such an ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl). ) Phenyl] -benzotriazole, 2- (2′-hydroxy-3 ′, 5-di-t-butylphenyl) -benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methyl) Phenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3', 5 ' -Di-t-amyl) benzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl) benzotriazole, 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6 -(2N-benzotriazol-2-yl) phenol] and the like, 2,4-dihydroxy-benzophenone, 2-hydroxy-4-methoxy-benzophenone, 2-hydroxy-4-methoxybenzophenone-5 -Sulfonic acid, 2-hydroxy-4-n-octyl-benzophenone, 2-hydroxy-4-n-dodecyloxy-benzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 2,2'- Benzophenone ultraviolet absorbers such as dihydroxy-4-methoxy-benzophenone and 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, salicylate ultraviolet absorbers such as phenyl salicylate and 4-t-butylphenyl salicylate, Ethyl-2-cyano-3, Cyanoacrylate-based UV absorbers such as 3-diphenyl-acrylate and 2-ethylhexyl-2-cyano-3,3′-diphenyl-acrylate, 2-ethoxy-3-tert-butyl-2′-ethyl-oxalic acid bisanilide, Oxalic acid anilide UV absorbers such as 2-ethoxy-2'-ethyl-oxalic acid bisanilide, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, etc. Benzoate ultraviolet absorbers, 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5-hydroxyphenol, 2- (2,4-dihydroxy) Phenyl) -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2,4-bis (2-hydroxy-4-but) Examples include triazine-based ultraviolet absorbers such as (ciphenyl) -6- (2,4-dibutoxyphenyl) -1,3-5-triazine, and the like, which effectively suppresses the decrease in the light reflectance of the light reflector. Therefore, a benzotriazole-based ultraviolet absorber is preferable. In addition, an ultraviolet absorber may be used independently or 2 or more types may be used together.

  The molecular weight of the ultraviolet absorber is preferably 250 or more, more preferably 300 to 500, and particularly preferably 400 to 500. When the light reflecting plate-forming resin composition is extruded to produce a light reflecting plate, the ultraviolet absorber having a molecular weight of less than 250 is easily volatilized from the surface of the light reflecting plate-forming resin composition. The volatilization of the ultraviolet absorber may cause defects such as uneven gloss, roughness, and tearing on the surface of the obtained light reflector. The light reflecting molded body obtained by thermoforming the light reflecting plate in which these defects are generated cannot uniformly exhibit excellent light reflecting performance.

  Moreover, 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 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 reflecting plate is preferably 0.01 to 0.5 parts by weight, more preferably 0.01 to 0.3 parts by weight with respect to 100 parts by weight of the thermoplastic resin. 0.01 to 0.2 parts by weight is particularly preferable.

  Further, the light reflecting plate may contain a hindered amine light reflection stabilizer. Such a hindered amine light stabilizer is not particularly limited, and examples thereof include bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate and bis (N-methyl-2,2,6,6). -Tetramethyl-4-piperidinyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) -2- (3,5-di-t-butyl-4-hydroxybenzyl) -2- n-butyl malonate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butane-tetracarboxylate, tetrakis (1,2,2,6,6- Pentamethyl-4-piperidyl) -1,2,3,4-butane-tetracarboxylate, (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butane-tetracarboxylate And a mixture of (2,2,6,6-tetramethyl-4-tridecyl) -1,2,3,4-butane-tetracarboxylate, (1,2,2,6,6-pentamethyl- 4-piperidyl) -1,2,3,4-butane-tetracarboxylate and (1,2,2,6,6-pentamethyl-4-tridecyl) -1,2,3,4-butane-tetracarboxylate And a mixture of {2,2,6,6-tetramethyl-4-piperidyl-3,9- [2,4,8,10-tetraoxaspiro (5.5) undecane] diethyl} -1,2, 3,4-butane-tetracarboxylate and {2,2,6,6-tetramethyl-β, β, β ′, β′-tetramethyl-3,9- [2,4,8,10-tetraoxa Spiro (5.5) undecane] diethyl} -1,2,3,4-butane-te Mixture with lacarboxylate, {1,2,2,6,6-pentamethyl-4-piperidyl-3,9- [2,4,8,10-tetraoxaspiro (5.5) undecane] diethyl}- 1,2,3,4-butane-tetracarboxylate and {1,2,2,6,6-pentamethyl-β, β, β ′, β′-tetramethyl-3,9- [2,4,8 , 10-Tetraoxaspiro (5.5) undecane] diethyl} -1,2,3,4-butane-tetracarboxylate, poly [6- (1,1,3,3-tetramethylbutyl) Imino-1,3,5-triazine-2,4-diyl], [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl -4-piperidyl) imino], 4-hydroxy-2,2,6,6-tetra A mixture of methyl-1-piperidineethanol and dimethyl succinate polymer, N, N ′, N ″, N ′ ″-tetrakis {4,6-bis [butyl- (N-methyl-2,2,6,6) -Tetramethylpiperidin-4-yl) amino] -triazin-2-yl} -4,7-diazadecane-1,10-diamine and the like, and may be used alone or in combination of two or more. .

  Moreover, when there is too little content of the hindered amine type light stabilizer in a light reflection board, there exists a possibility that the fall of the light reflectivity of a light reflection board cannot be suppressed. On the other hand, even if the content of the hindered amine light stabilizer in the light reflector is excessive, the effect of suppressing the decrease in the light reflectance of the light reflector is not changed, and the light reflector is colored by the coloring of the hindered amine light stabilizer itself. There is a risk of lowering the light reflectance. Therefore, the content of the hindered amine light stabilizer in the light reflector is preferably 0.01 to 0.5 parts by weight, more preferably 0.01 to 0.3 parts by weight with respect to 100 parts by weight of the thermoplastic resin. 0.01 to 0.2 parts by weight is particularly preferable.

  Here, the deterioration of the thermoplastic resin is caused by the cleavage of the polymer main chain. Specifically, radicals are generated by heat, light, and the like, and the generated radicals react with oxygen to turn into peroxy radicals, drawing hydrogen from the main chain into hydroperoxides. Thereafter, hydroperoxide is decomposed by the action of heat, light, and the like, becomes an alkoxy radical, cuts the polymer main chain, and a radical is generated as the polymer main chain is cut. By repeating this reaction cycle, the polymer main chain is cleaved to lower the molecular weight, and the thermoplastic resin deteriorates. This deterioration of the thermoplastic resin causes yellowing of the thermoplastic resin, resulting in a decrease in the light reflectance of the light reflecting plate.

  Therefore, as described above, the light reflecting plate preferably uses a coated titanium oxide formed by coating the surface of titanium oxide with a coating layer containing aluminum oxide and silicon oxide, and the titanium oxide and the thermoplastic resin are used. In addition, UV rays incident on titanium oxide are blocked by the coating layer as much as possible to prevent oxidative degradation of the thermoplastic resin due to the photocatalytic action of titanium oxide, and photochemistry in the titanium oxide crystals. Discoloration to dark gray due to an increase in oxygen defects due to the change is prevented.

  Further, as described above, the primary reflection agent, the secondary antioxidant, the ultraviolet absorber, and the hindered amine light stabilizer are added to the light reflecting plate to cause yellowing or coating oxidation due to deterioration of the thermoplastic resin. This is preferable because the photochemical change of titanium can be suppressed to further prevent the light reflectance of the light reflecting plate from decreasing.

  Specifically, by adding an ultraviolet absorber and a hindered amine light stabilizer, yellowing due to deterioration of the thermoplastic resin is more effectively prevented by the light stabilizing effect of the thermoplastic resin, and the titanium oxide It is possible to prevent the oxidative degradation of the thermoplastic resin due to the activation and further suppress the photochemical change.

  On the other hand, as described above, the ultraviolet absorber and the hindered amine light stabilizer have the ability to suppress the oxidative decomposition of the polyolefin resin by titanium oxide, but the inhibitory power is not sufficient, and the ultraviolet absorber. In addition, the hindered amine light stabilizer itself may be oxidized and decomposed by titanium oxide.

  Therefore, in addition to UV absorbers and hindered amine light stabilizers, primary antioxidants and secondary antioxidants are added to light-stabilize polyolefin resins by trapping radical reactions and ionic decomposition of hydroperoxides. In addition to ensuring the prevention of yellowing due to deterioration, the oxidative decomposition of the UV absorber and the hindered amine light stabilizer by titanium oxide is more reliably prevented.

  That is, in addition to preventing yellowing due to deterioration of the thermoplastic resin by the primary antioxidant and the secondary antioxidant, the decomposition of the UV absorber and the hindered amine light stabilizer by titanium oxide is further reliably prevented, This protected UV absorber and hindered amine light stabilizer further prevent the oxidative degradation of the thermoplastic resin by titanium oxide and suppress the photochemical change, and the initial light reflectivity is short. As a result, it is possible to more reliably prevent a situation in which the light beam is reduced, and to maintain an excellent light reflectance even over a long period of time.

  Furthermore, the light reflecting plate may contain a copper damage inhibitor (metal deactivator). Addition of copper damage prevention agent in the light reflector makes it easier to deteriorate even when the light reflector comes into contact with metals such as copper or when heavy metal ions such as copper ions act on the light reflector. Copper ions, which are factors, can be captured as a chelate compound. When the light reflector is incorporated into various liquid crystal display devices and lighting devices, even if the light reflector comes into contact with a metal such as copper, It is possible to prevent the plastic resin from being deteriorated and yellowing.

  Examples of the copper damage inhibitor (metal deactivator) include hydrazine compounds such as N, N-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, 3 -(3,5-di-tetra-butyl-4-hydroxyphenyl) propionyl dihydride and the like.

  And when there is too little content of the copper damage prevention agent (metal deactivator) in a light reflection plate, there exists a possibility that the effect which added the copper damage prevention agent may not express. On the other hand, when there is too much content of the copper damage prevention agent (metal deactivator) in a light reflection board, there exists a possibility that the light reflectivity of a light reflection board may fall. Therefore, the content of the copper damage preventing agent (metal deactivator) in the light reflecting plate is preferably 0.1 to 1.0 part by weight with respect to 100 parts by weight of the thermoplastic resin.

  Further, an antistatic agent may be added to the light reflecting plate. By adding the antistatic agent in this way, the light reflecting plate can be prevented from being charged, dust and dirt can be prevented from adhering to the light reflecting plate, and the light reflectance of the light reflecting plate can be lowered. Can be prevented.

  As such an antistatic agent, for example, ionomers such as polyethylene oxide, polypropylene oxide, polyethylene glycol, polyester amide, polyether ester amide, and ethylene-methacrylic acid copolymer, and fourth polymers such as polyethylene glycol methacrylate copolymer are used. A class ammonium salt, a polymer type antistatic agent such as a block copolymer having a structure in which an olefinic block and a hydrophilic block described in JP-A-2001-278985 are bonded alternately and repeatedly, an inorganic salt, a polyhydric alcohol , Metal compounds, carbon and the like.

  And if there is too little content in the light reflection plate of the antistatic agent except a polymer type antistatic agent, the effect which added the antistatic agent may not express. On the other hand, if the content of the antistatic agent excluding the polymer antistatic agent in the light reflecting plate is too large, not only the effect corresponding to the addition concentration of the antistatic agent can be obtained, but also the effect of the antistatic agent can be obtained. There may be a reduction or significant bleeding out, coloring and yellowing due to light. Therefore, the content of the antistatic agent excluding the polymer antistatic agent in the light reflecting plate is preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the thermoplastic resin.

  Further, the content of the polymer type antistatic agent in the light reflecting plate is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the thermoplastic resin for the same reason as described above.

  Furthermore, in addition to copper damage inhibitors (metal deactivators) and antistatic agents, the light reflecting plate includes dispersants such as metal stearates, quenchers, lactone processing stabilizers, fluorescent brighteners, A crystal nucleating agent or the like may be added.

  If the thickness of the light reflecting plate is too thin, the rigidity of the light reflecting plate may be reduced, and the light reflecting plate may be bent. In addition, the light reflecting plate may be obtained by thermoforming the light reflecting plate. There is a possibility that a thin-walled portion is likely to occur. Moreover, when the thickness of the light reflecting plate is too thick, the thickness and weight of the device incorporating the light reflecting molded body may increase. Therefore, the thickness of the light reflecting plate 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.

  Next, a method for manufacturing the light reflecting plate will be described. As a method for producing the light reflecting plate, a known method is used, and for example, a light reflecting plate forming resin composition containing a thermoplastic resin and an inorganic filler is used.

  In addition to the thermoplastic resin and the inorganic filler, the light reflecting plate-forming resin composition may contain other antioxidants such as a primary antioxidant, a secondary antioxidant, an ultraviolet absorber, and a hindered amine light stabilizer as necessary. It preferably contains an additive. It should be noted that other thermoplastic fillers used in the light reflecting plate forming resin composition, inorganic fillers such as coated titanium oxide, primary antioxidants, secondary antioxidants, ultraviolet absorbers and hindered amine light stabilizers. The explanation about the additive is as described above.

  Further, the light reflecting plate forming resin composition is prepared in advance as a masterbatch containing a thermoplastic resin and an inorganic filler, and the masterbatch, the thermoplastic resin, and, if necessary, a primary antioxidant, a secondary It preferably contains other additives such as antioxidants, UV absorbers and hindered amine light stabilizers. Thus, the dispersibility of the inorganic filler in the light reflecting plate forming resin composition can be improved by using the master batch containing the inorganic filler. Further, in the case of using a coated titanium oxide in which the surface of titanium oxide is coated with a coating layer containing aluminum oxide and silicon oxide and the water content is 0.5% by weight or less as the inorganic filler. However, in the masterbatch, the coated titanium oxide with a water content of 0.5% by weight or less is completely coated with the thermoplastic resin, and there is almost no coated titanium oxide that is exposed without being coated with the thermoplastic resin. do not do. Therefore, even if the masterbatch is left for a long time, the moisture content of the coated titanium oxide contained in the masterbatch is kept constant without substantially changing.

  The production of the masterbatch is not particularly limited, but after supplying the inorganic filler and the thermoplastic resin to the extruder at a predetermined weight ratio and melt-kneading to obtain a melt-kneaded product, the melt-kneaded product is extruded into the extruder. Is preferably carried out by an extrusion method. In addition, when using a coated titanium oxide in which the surface of titanium oxide is coated with a coating layer containing aluminum oxide and silicon oxide and having a water content of 0.5% by weight or less as an inorganic filler, Also when using, it is preferable to prepare a masterbatch using coated titanium oxide that has been preliminarily heated and dried to a water content of 0.5% by weight or less as described above.

  When a melt-kneaded product is obtained by melt-kneading an inorganic filler and a thermoplastic resin in an extruder, an extruder having a volatile component removing means is used to remove the volatile matter generated from the melt-kneaded product in the extruder. It is preferable to discharge to the outside. By such a method, even when the coated titanium oxide is used as the inorganic filler, the hydration water contained in the coated layer of the coated titanium oxide can be removed more highly.

  As an extruder having a volatile content removing means, for example, a vent type provided with a vent port for discharging gas inside the cylinder to the outside at the middle part of the cylinder of the extruder for melting and kneading the inorganic filler and the thermoplastic resin. An extruder or the like is preferably used. According to the vent type extruder, the gas inside the cylinder can be sucked from the vent port and discharged to the outside using a vacuum pump or the like.

  When the gas is sucked from the vent port, the pressure in the cylinder is preferably 7.5 to 225 mmHg (1 to 30 kPa), and more preferably 22.5 to 150 mmHg (3 to 20 kPa). By setting the pressure in the cylinder within the above range, water of hydration contained in the coated titanium oxide contained in the melt-kneaded product can be removed even during melt-kneading. Moreover, 180-290 degreeC is preferable and, as for the temperature of the melt-kneaded material at the time of melt-kneading, 180-270 degreeC is more preferable.

  The resin composition for forming a light reflecting plate includes a thermoplastic resin and an inorganic filler, and other additives such as a primary antioxidant, a secondary antioxidant, an ultraviolet absorber, and a hindered amine light stabilizer as necessary. Is preferably manufactured by supplying the mixture to an extruder and melt-kneading so that each component is contained in a desired weight ratio in the finally obtained light reflecting plate. In the case of using a masterbatch, the resin composition for forming a light reflecting plate includes a masterbatch containing a thermoplastic resin and an inorganic filler, a thermoplastic resin, and, if necessary, a primary antioxidant and a secondary antioxidant. , Other additives such as UV absorbers and hindered amine light stabilizers are supplied to the extruder and melt-kneaded so that each component is contained in a desired weight ratio in the finally obtained light reflecting plate It is preferable to manufacture by doing.

  The resin composition for forming a light reflecting plate is preferably manufactured by supplying a thermoplastic resin and an inorganic filler to a general-purpose kneading apparatus such as an extruder and melt-kneading. The resin composition for use may be molded into a predetermined shape such as a pellet.

  And the light reflection board which consists of a non-foaming sheet | seat can be manufactured by shape | molding the resin composition for light reflection board formation mentioned above in a sheet form. In order to form the light reflecting plate forming resin composition into a sheet shape, the light reflecting plate forming resin composition may be formed into a sheet shape by a known method such as an inflation method, a T-die method, or a calendar method. The die method is preferred. 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.

  When a resin composition for forming a light reflecting plate is obtained by supplying a thermoplastic resin and an inorganic filler to an extruder and melt-kneading in the extruder, the resin composition for forming a light reflecting plate is removed from the extruder. A light reflector can be produced by direct extrusion. In addition, when using a light reflecting plate forming resin composition molded into a predetermined shape such as a pellet, after supplying the molded light reflecting plate forming resin composition to an extruder and melt-kneading, A light reflector can be produced by extrusion from an extruder.

  In addition, when a resin composition for forming a light reflector is melt-kneaded in an extruder and then formed into a sheet, an extruder having a volatile component removing means such as a vent-type extruder is used to form a light reflector. It is preferable to discharge the volatile matter generated from the light reflecting plate forming resin composition to the outside of the extruder during melt kneading of the resin composition. The vent type extruder is the same as that described above in the master batch.

  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, it is applied to at least one surface of the sheet-like extrudate. It is preferable to perform mirror surface processing. According to the mirror surface processing, a light reflecting plate with improved surface smoothness of the sheet-like extrudate can be obtained. In this way, according to the light reflecting plate having excellent surface smoothness, as will be described later, when thermoforming using a mold, the uneven portion formed on the molding surface of the mold is accurately applied to the surface of the light reflecting plate. Thus, a light reflection molded article having more excellent light reflection performance and light diffusion performance can be produced.

  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.

  A sheet-like support may be laminated and integrated on one surface of the light reflecting plate to form a laminate. Examples of such a support include a biaxially stretched polypropylene resin film, a biaxially stretched polyester resin film, a polyamide resin film, and paper. Here, the polypropylene resin is preferably polypropylene. Preferred examples of the polyester resin include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polylactic acid. As the polyamide-based resin, nylon-6, nylon-6, 6 and the like are preferable.

  Further, a metal foil can be laminated and integrated on one surface of the light reflecting plate to form a laminated body. The metal foil is preferably an aluminum foil. Thus, the laminated body which has the outstanding light reflectivity is obtained by laminating | stacking and integrating metal foil.

  When a sheet-like support or metal foil is laminated and integrated on one surface of the light reflection plate, the mirror treatment surface of the light reflection plate is exposed when the light reflection plate is mirror-finished. In this state, it is preferable to laminate and integrate a sheet-like support or metal foil on the light reflecting plate.

  In order to laminate and integrate the support or metal foil on the light reflecting plate, it is not particularly limited, and may be performed using a known method such as a heat laminating method, a dry laminating method, and an extrusion laminating method.

  The light reflecting plate does not require a stretching step in its production, has excellent thermoformability, and produces a light reflecting molded body by thermoforming the light reflecting plate using a mold. Can do. Specifically, after heating the light reflecting plate, the light reflecting plate is pressed against the molding surface of the mold to be thermoformed along the molding surface of the mold, and on the mold molding surface of the light reflecting plate. The light reflecting molded body is manufactured by transferring the uneven portions formed on the molding surface of the mold to the contacting surface and forming the uneven portions on the surface of the light reflecting plate. In the present invention, the molding surface of the mold refers to the surface of the mold that is in contact with the surface of the light reflecting molded body obtained by thermoforming the light reflecting plate.

  In addition, it is not necessary that the concavo-convex part is formed on the entire molding surface of the mold, and the concavo-convex part may be formed on a part of the molding surface of the mold that is in contact with the light reflecting plate. For example, when the mold is composed of male and female molds, the light reflecting plate is disposed between the male and male molds in a heated state, and the light reflecting plate is thermoformed by clamping the male and female molds in this state. The concave and convex portions may be formed on both of the molding surfaces of the female mold and the male mold, or the concave and convex portions are formed only on the molding surface of either the female mold or the male mold. May be.

  If the surface roughness Ra of the concavo-convex portion on the molding surface of the mold is small, the light diffusion performance of the light reflecting molded body is lowered, and if large, the diffusibility of the light reflected from the light reflecting molded body is non-uniform, Since the diffuse reflectance of the light reflected from the light reflection molded body may be lowered, it is limited to 1 to 20 μm, and preferably 1 to 15 μm.

  If the average spacing Sm of the irregularities formed on the molding surface of the mold is small, the light diffusibility of the light reflecting molded body may be reduced. If it is large, the light reflected from the light reflecting molded body Diffusivity becomes non-uniform and the diffuse reflectance of the light reflected from the light reflecting molded body may be lowered, so it is limited to 5 to 300 μm, and preferably 10 to 130 μm.

  If the maximum height (Ry) of the unevenness formed on the molding surface of the mold is small, the light diffusibility of the light reflecting molded body may be lowered. If it is large, it is reflected from the light reflecting molded body. The diffusibility of the emitted light becomes non-uniform, and the diffuse reflectance of the light reflected from the light reflection molded article may be lowered. Therefore, 5 to 80 μm is preferable, 10 to 50 μm is more preferable, and 10 to 30 μm is particularly preferable. preferable.

  The surface roughness Ra of the concavo-convex portion of the molding surface of the mold is a value measured at a reference length of 2.5 mm and an evaluation length of 12.5 mm in accordance with JIS B0601. The average interval Sm between the projections and depressions formed on the projections and depressions on the molding surface of the mold is a value measured at a reference length of 2.5 mm and an evaluation length of 12.5 mm in accordance with JIS B0601. The maximum height (Ry) of the unevenness of the unevenness formed on the molding surface of the mold is a value measured at a reference length of 2.5 mm and an evaluation length of 12.5 mm in accordance with JIS B0601. . Specifically, the surface roughness Ra, the average interval Sm, and the maximum height (Ry) are obtained from Keyence Corporation under the trade names “Double Scan High Precision Laser Measuring Instrument LT-9500” and “Double Scan High Precision Laser Measuring Machine LT- 9010M "and a measuring instrument marketed under the trade name" Non-contact contour shape / roughness measuring system MAP-2DS "from Combs can be combined for measurement.

  The method for forming the concavo-convex portion on the molding surface of the mold is not particularly limited, and examples thereof include a shot blasting method and a knurling method. In the case of the shot blasting method, No. 20 to 100 are used as the polishing (projection) agent, and in the present invention, since it is necessary to form desired irregularities on the surface of the light reflecting plate, No. 20 to 80 are preferable. When the count of shot blasting is small, there is a possibility that a release processing surface described later is not stably fixed on the molding surface of the mold. The degree of unevenness of the molding surface of the mold is adjusted by the type (particle size, composition, hardness) of the polishing (projection) agent, the projection speed (pressure), the processing time, the projection amount, etc. That's fine.

  In order to improve releasability from the light reflecting plate, the mold surface of the mold has a fluorine-based resin such as polytetrafluoroethylene, DLC (Diamond-Like Carbon), molybdenum disulfide, titanium nitride (TiN). ) Or the like may be formed. If the thickness of the release treatment layer is thin, the effect of forming the release treatment layer may not be manifested, and if it is thick, the unevenness of the molding surface of the mold may be small or disappear, so 1 to 90 μm. Is preferable, and 1 to 40 μm is more preferable. In addition, when the mold release processing surface is formed on the surface of the molding surface of the mold, the surface roughness Ra of the concavo-convex portion of the molding surface of the mold, the average interval Sm of the concavo-convex portion, and the maximum of the concavo-convex portion of the concavo-convex portion The height (Ry) is defined as the surface roughness Ra, the average interval Sm between the irregularities, and the maximum height (Ry) of the irregularities.

  The material of the mold is not particularly limited, and a known metal material is used, but an aluminum alloy or a copper alloy is preferable.

  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 thereof include draw molding and hot plate heating type air pressure molding. In the molding method, it is preferable to use a mold whose temperature can be adjusted.

  In the obtained light reflecting molded body, the unevenness of the uneven portion formed on the molding surface of the mold is transferred to the surface that is in contact with the uneven portion of the molding surface of the mold to form an uneven surface. . The light reflecting molded body exhibits excellent light diffusion performance due to the uneven surface of the light reflecting molded body.

  If the surface roughness Ra of the uneven surface of the light reflection molded body is small, the light diffusibility of the light reflection molded body may be reduced. If it is large, the diffusibility of the light reflected from the light reflection molded body is not uniform. Thus, the diffuse reflectance of light reflected from the light reflecting molded body may be lowered, so that it is limited to 1 to 20 μm, and preferably 1 to 15 μm.

  The average spacing Sm of the irregularities on the irregular surface of the light reflection molded body may reduce the light diffusibility of the light reflection molded body, and if large, the diffusibility of the light reflected from the light reflection molded body becomes non-uniform, Since the diffuse reflectance of the light reflected from the light reflection molding may be lowered, it is limited to 5 to 300 μm, and preferably 10 to 130 μm.

  If the maximum height (Ry) of the irregularities on the irregular surface of the light reflection molded body is small, the light diffusibility of the light reflection molded body may be reduced. If it is large, the diffusion of light reflected from the light reflection molded body may be reduced. Since the property becomes non-uniform and the diffuse reflectance of the light reflected from the light reflection molded article may be lowered, 5 to 80 μm is preferable, 10 to 50 μm is more preferable, and 10 to 30 μm is particularly preferable.

  The surface roughness Ra of the concavo-convex surface of the light reflecting molded body is a value measured at a reference length of 2.5 mm and an evaluation length of 12.5 mm in accordance with JIS B0601. The average interval Sm of the irregularities on the irregular surface of the light reflecting molded body is a value measured at a reference length of 2.5 mm and an evaluation length of 12.5 mm in accordance with JIS B0601. The maximum height (Ry) of the unevenness on the uneven surface of the light reflecting molded body is a value measured at a reference length of 2.5 mm and an evaluation length of 12.5 mm in accordance with JIS B0601. Specifically, the surface roughness Ra, the average interval Sm, and the maximum height (Ry) are obtained from Keyence Corporation under the trade names “Double Scan High Precision Laser Measuring Instrument LT-9500” and “Double Scan High Precision Laser Measuring Machine LT- 9010M "and a measuring instrument marketed under the trade name" Non-contact contour shape / roughness measuring system MAP-2DS "from Combs can be combined for measurement.

  The light reflection molded article of the present invention is preferably used in 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. As described above, the light reflecting molded article of the present invention has excellent light reflecting performance and light diffusing performance. Therefore, when such a light reflecting molded article is used in a backlight unit of a liquid crystal display device, luminance reduction and unevenness are achieved. It is possible to provide a liquid crystal display device in which the occurrence of the above is suppressed.

  When the light reflection molded body is used in a backlight unit of a liquid crystal display device, the light reflection molded body is used by being incorporated in a direct light backlight, a sidelight backlight, or a planar light source backlight constituting the liquid crystal display device. be able to.

  FIG. 1 shows a schematic diagram of a sidelight type backlight unit of a liquid crystal display device in which the light reflection molded article of the present invention is used. The liquid crystal display device shown in FIG. 1 includes a light reflection molded body 10, a light guide plate 20 disposed on the light reflection molded body 10 so as to face the uneven surface 11, and a side of the light guide plate 20. A light emitting source 30 that emits light to the light guide plate 20 and a lamp reflector 40 for reflecting the light emitted from the light emitting source 30 to the light guide plate 20 are provided. Examples of the light emission source 30 include a cooling cathode and an LED.

  In the liquid crystal display device, the light incident on the light guide plate 20 from the light emitting light source 30 is led out of the light guide plate 20 from the surface of the light guide plate 20 by repeatedly reflecting between the front and back surfaces of the light guide plate 20. Further, the light derived from the back surface of the light guide plate 20 is diffused and reflected so as to be uniform toward the front surface side of the light guide plate 20 by the uneven surface 11 formed on the surface of the light reflection molded body 10. Further, when light derived from the back surface of the light guide plate 20 passes through the light diffusion layer 20, the light is reflected by the light reflecting molded body 10 toward the front surface side of the light guide plate 20. Thus, the luminance of the liquid crystal display device can be improved by combining the light guide plate 20 and the light reflection molded body 10 with the light emitting source.

  In addition to the above-described backlight unit of the liquid crystal display device, the light reflection molded body is also preferably used for lighting devices for advertisements and billboards. Below, an example of the illuminating device using a light reflection molded object is demonstrated, referring drawings.

  When the light reflection molded body 10 is used for a lighting device for advertisements or billboards, the light reflection molded body 10 is thermoformed into a shape as shown in FIGS. 2 and 3, for example. Specifically, it has a plurality of inverted truncated quadrangular pyramid-shaped recesses 12, 12... Formed continuously in the vertical and horizontal directions, and the inner bottom surface 13 of the recesses 12, 12. A through hole 13a is formed as a light source disposition portion for disposing the inner peripheral surface 14 of the recesses 12, 12,... Is formed entirely from the uneven surface of the light reflecting molded body 10, It is formed on a light reflecting surface that reflects light emitted from the light source. Therefore, at the time of thermoforming the light reflecting plate, the uneven portion of the molding surface of the mold is in contact with the surface of the light reflecting plate, which will form the inner peripheral surface 14 of the concave portion 12 of the light reflecting molded body. The light reflector is thermoformed using a mold.

  And the illuminating device using the light reflection molded object thermoformed as mentioned above 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 10 and a light emitting diode L is disposed in a housing 60. The casing 60 includes a flat rectangular bottom surface 61 having a size slightly larger than the light reflecting molded body 10 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. In the state where the light reflection molded body 10 is overlaid on the light source body 70, the positions of 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 matched.

  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). 10 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 reflecting molded body 10 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 (uneven surface) of the concave portion 12 of the light reflecting molded body 10 is reflected and travels once or multiple times on the inner peripheral surface. The direction is directed toward the frosted glass or optical sheet 80 and enters the frosted glass or optical sheet 80. It is preferable that the light reflection molded body 10 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 10, and again in the direction of the light reflection molded body 10. Although incident, the light incident again in the light reflecting molded body 10 is reflected on the inner peripheral surface of the recess 12 and is incident on the frosted glass or the optical sheet 80 again.

  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.

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

Example 1
First, coated titanium oxide A (trade name “CR-93” manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.28 μm) was prepared. In this coated titanium oxide A, the surface of rutile type titanium oxide was coated with a coating layer containing aluminum oxide and silicon oxide. In the coated titanium oxide A, when the amount of aluminum oxide was quantified by fluorescent X-ray analysis, it was 3.1% by weight in terms of Al ₂ O ₃ with respect to the total weight of titanium dioxide. Further, when the amount of silicon oxide in the coated titanium oxide A was quantified by fluorescent X-ray analysis, it was 4.2% by weight in terms of SiO ₂ with respect to the total weight of titanium dioxide.

Next, the hydrated water contained in the coated titanium oxide was reduced by heating and drying the coated titanium oxide A at 100 ° C. for 5 hours. 53.8 parts by weight of coated titanium oxide A with reduced hydration water and homopolypropylene (trade name “PL500A” manufactured by Sun Allomer, melt flow rate: 3.3 g / 10 min, density: 0.9 g / cm ³ ) 40 A master batch of coated titanium oxide A was prepared by melting and kneading the parts by weight with a bent twin screw extruder having a diameter of 120 mm at 230 ° C. and pelletizing. When the coated titanium oxide A and homopolypropylene are melt-kneaded in the cylinder of the vent type twin screw extruder, the pressure in the cylinder is 60 mmHg (8 kPa) and the gas in the cylinder is vented from the vent port by a vacuum pump. Was discharged to the outside.

And 93.8 parts by weight of the master batch, 60 parts by weight of homopolypropylene (trade name “PL500A” manufactured by Sun Aroma Co., Ltd., melt flow rate: 3.3 g / 10 min, density: 0.9 g / cm ³ ), phenolic antioxidant 0.15 parts by weight of an agent (trade name IRGANOX (registered trademark) 1010 manufactured by BASF), 0.15 part by weight of a phosphorus-based antioxidant (trade name IRGAFOS 168 manufactured by BASF), a benzotriazole-based ultraviolet absorber 1 (molecular weight 315. 8, 0.15 parts by weight of BASF brand name TINUVIN (registered trademark) 326) and 0.15 parts by weight of a hindered amine light stabilizer (BASF brand name TINUVIN (registered trademark) 111) having a diameter of 120 mm A resin assembly for forming a light reflector by feeding to a bent single screw extruder and melt-kneading at 220 ° C. Extruded into a sheet form from a T-die (sheet width: 1000 mm, slit interval: 0.2 mm, temperature 200 ° C.) attached to the tip of the extruder. I got a thing. Next, this sheet-like extrudate is supplied between a pair of rolls consisting of a mirror roll whose outer peripheral surface is formed into a mirror surface and a support roll disposed opposite to the mirror roll, and the mirror roll is supplied to the sheet. By pressing against the surface of the shaped extrudate, a non-foamed light reflector having a thickness of 0.2 mm and a density of 1.3 g / cm ³ was obtained. When melt-kneading the resin composition in the cylinder of a vent type single screw extruder, the pressure in the cylinder is 60 mmHg (8 kPa), and the gas in the cylinder is discharged from the vent port to the outside by a vacuum pump. did.

  On the other hand, a mold 8 for thermoforming the light reflecting plate was prepared. As shown in FIG. 5, the mold 8 is formed of male and female molds 81 and 82, and a recess 811 of the female mold 81 is formed. The male mold 82 includes a recess 811 of the female mold 81. Convex part 821 was formed corresponding to the above, and the surface of convex part 821 was the molding surface. The molding surface of the male mold 82 was provided with an uneven portion 821a over the entire surface. With respect to the concavo-convex portion 821a formed on the molding surface of the male mold 82, the surface roughness Ra, the average interval Sm and the maximum height (Ry) of the concavo-convex portions are as shown in Table 1. The surface of the recess 811 of the female die 81 was a molding surface, and no irregularities were formed on the molding surface, and the entire surface was formed as a flat surface.

  After heating the light reflecting plate to 150 ± 5 ° C., the light reflecting plate is thermoformed by placing the light reflecting plate between the male and female molds 81 and 82 and clamping the male and female molds 81 and 82 thereon. Thus, a light reflecting molded body 9 was obtained. The light reflecting plate was disposed between the male and female molds 81 and 82 so that the mirror-finished surface of the light reflecting plate was in contact with the uneven portion 821a of the molding surface of the male mold 82.

  As shown in FIG. 6, the light reflecting molded body 9 has a flat rectangular bottom surface portion 91 and both side wall portions 92 extending upward from both end edges of the bottom surface portion 91. In addition, irregularities were formed on the upper surface of the bottom surface portion 91 and the inner surfaces of the side wall portions 92, 92 to form irregular surfaces 91a, 92a, 92a.

(Example 2)
A light-reflecting molded article was produced in the same manner as in Example 1 except that coated titanium oxide B (trade name “CR-90” manufactured by Ishihara Sangyo Co., Ltd., average particle diameter of 0.25 μm) was used instead of coated titanium oxide A. did.

In addition, the surface of the rutile titanium oxide was covered with a coating layer containing aluminum oxide and silicon oxide in the coated titanium oxide B. When the amount of aluminum oxide in the coated titanium oxide B was quantified by fluorescent X-ray analysis, it was 2.7% by weight in terms of Al ₂ O ₃ with respect to the total weight of titanium dioxide. Further, when the amount of silicon oxide in the coated titanium oxide B was quantified by fluorescent X-ray analysis, it was 3.6% by weight with respect to the total weight of titanium dioxide in terms of SiO ₂ .

(Example 3)
A light-reflecting molded body was produced in the same manner as in Example 1 except that coated titanium oxide C (trade name “CR-80” manufactured by Ishihara Sangyo Co., Ltd., average particle diameter of 0.25 μm) was used instead of coated titanium oxide A. did.

In the coated titanium oxide C, the surface of rutile type titanium oxide was coated with a coating layer containing aluminum oxide and silicon oxide. When the amount of aluminum oxide in the coated titanium oxide C was quantified by fluorescent X-ray analysis, it was 3.3% by weight in terms of Al ₂ O ₃ with respect to the total weight of titanium dioxide. Further, when the amount of silicon oxide in the coated titanium oxide C was quantified by fluorescent X-ray analysis, it was 1.8% by weight in terms of SiO ₂ with respect to the total weight of titanium dioxide.

Example 4
A light-reflecting molded article was produced in the same manner as in Example 1 except that coated titanium oxide D (trade name “CR-63” manufactured by Ishihara Sangyo Co., Ltd., average particle size 0.21 μm) was used instead of coated titanium oxide A. did.

In addition, as for the covering titanium oxide D, the surface of rutile type titanium oxide was coat | covered with the coating layer containing an aluminum oxide and a silicon oxide. When the amount of aluminum oxide in the coated titanium oxide D was quantified by fluorescent X-ray analysis, it was 1.4% by weight with respect to the total weight of titanium dioxide in terms of Al ₂ O ₃ . Further, when the amount of silicon oxide in the coated titanium oxide D was quantified by fluorescent X-ray analysis, it was 0.7% by weight with respect to the total weight of titanium dioxide in terms of SiO ₂ .

(Example 5)
A light-reflecting molded article was produced in the same manner as in Example 1 except that coated titanium oxide E (trade name “CR-50”, manufactured by Ishihara Sangyo Co., Ltd., average particle diameter of 0.25 μm) was used instead of coated titanium oxide A. did.

In addition, as for the covering titanium oxide E, the surface of rutile type titanium oxide was coat | covered with the coating layer containing an aluminum oxide and a silicon oxide. When the amount of aluminum oxide in the coated titanium oxide E was quantified by fluorescent X-ray analysis, it was 2.3% by weight in terms of Al ₂ O ₃ with respect to the total weight of titanium dioxide. Further, when the amount of silicon oxide in the coated titanium oxide E was quantified by fluorescent X-ray analysis, it was 0.1% by weight in terms of SiO ₂ with respect to the total weight of titanium dioxide.

(Examples 6 to 10)
As shown in Table 1, the type of coated titanium oxide was changed, and in place of the benzotriazole ultraviolet absorber 1, a benzotriazole ultraviolet absorber 2 (molecular weight 447.6, trade name TINUVIN (registered trademark) manufactured by BASF) Except that 234) was used, a light reflection molded article was produced in the same manner as in Example 1.

(Examples 11 and 12)
As shown in Table 1, the compounding amount of the coated titanium oxide was changed, and the benzotriazole ultraviolet absorber 2 (molecular weight 447.6, trade name TINUVIN (registered trademark) manufactured by BASF) was used instead of the benzotriazole ultraviolet absorber 1 ) A light reflection molded article was produced in the same manner as in Example 1 except that 234) was used.

(Example 13)
First, coated titanium oxide A (trade name “CR-93” manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.28 μm) was prepared. In this coated titanium oxide A, the surface of rutile type titanium oxide was coated with a coating layer containing aluminum oxide and silicon oxide. In the coated titanium oxide A, when the amount of aluminum oxide was quantified by fluorescent X-ray analysis, it was 3.1% by weight in terms of Al ₂ O ₃ with respect to the total weight of titanium dioxide. Further, when the amount of silicon oxide in the coated titanium oxide A was quantified by fluorescent X-ray analysis, it was 4.2% by weight in terms of SiO ₂ with respect to the total weight of titanium dioxide.

Next, the hydrated water contained in the coated titanium oxide was reduced by heating and drying the coated titanium oxide A at 100 ° C. for 5 hours. 53.8 parts by weight of coated titanium oxide A with reduced hydration water and homopolypropylene (trade name “PL500A” manufactured by Sun Allomer, melt flow rate: 3.3 g / 10 min, density: 0.9 g / cm ³ ) 40 A master batch of coated titanium oxide A was prepared by melting and kneading the parts by weight with a bent twin screw extruder having a diameter of 120 mm at 230 ° C. and pelletizing. When the coated titanium oxide A and homopolypropylene are melt-kneaded in the cylinder of the vent type twin screw extruder, the pressure in the cylinder is 60 mmHg (8 kPa) and the gas in the cylinder is vented from the vent port by a vacuum pump. Was discharged to the outside.

Next, 93.8 parts by weight of the master batch, 60 parts by weight of homopolypropylene (trade name “PL500A” manufactured by Sun Allomer, melt flow rate: 3.3 g / 10 min, density: 0.9 g / cm ³ ), phenolic oxidation 0.15 parts by weight of an inhibitor (trade name IRGANOX (registered trademark) 1010, manufactured by BASF), 0.15 parts by weight of a phosphorus-based antioxidant (trade name IRGAFOS 168, manufactured by BASF), a benzotriazole-based ultraviolet absorber 1 (molecular weight 315) .8, 0.15 parts by weight of BASF brand name TINUVIN (registered trademark) 326) and 0.15 parts by weight of a hindered amine light stabilizer (trade name TINUVIN (registered trademark) 111) manufactured by BASF, 120 mm in diameter A resin composition for forming a light reflector by supplying to a bent type single screw extruder and melting and kneading at 220 ° C. It was obtained. This resin composition is extruded in a strand form from a nozzle die attached to the tip of a vent type single screw extruder, and this strand is cut every 2.5 mm in length to form a cylinder having a diameter of 2.5 mm. Thus, a pelletized resin composition for forming a light reflecting plate was obtained. In addition, when melt-kneading the resin composition for forming a light reflecting plate in a cylinder of a vent type single-screw extruder, the pressure in the cylinder is set to 60 mmHg (8 kPa), and a vacuum pump is used to bring the inside of the cylinder into the cylinder. The gas was discharged to the outside.

Then, the pelletized resin composition for forming a light reflector is supplied to a vent type single screw extruder having a diameter of 120 mm, melt-kneaded at 220 ° C., and then attached to a tip of the extruder (sheet width) : 1000 mm, slit interval: 0.2 mm, temperature 200 ° C.) to obtain a sheet-like extrudate. Next, this sheet-like extrudate is supplied between a pair of rolls consisting of a mirror roll whose outer peripheral surface is formed into a mirror surface and a support roll disposed opposite to the mirror roll, and the mirror roll is supplied to the sheet. By pressing against the surface of the shaped extrudate, a non-foamed light reflector having a thickness of 0.2 mm and a density of 1.3 g / cm ³ was obtained. When melt-kneading the light reflecting plate forming resin composition pelletized in the cylinder of the vent type single screw extruder, the pressure in the cylinder is 60 mmHg (8 kPa) and the cylinder is opened from the vent port by a vacuum pump. The gas inside was discharged to the outside. The light reflecting plate was thermoformed in the same manner as in Example 1 to obtain a light reflecting molded body. With respect to the concavo-convex portion 821a formed on the molding surface of the male mold 82, the surface roughness Ra, the average interval Sm and the maximum height (Ry) of the concavo-convex portions were as shown in Table 2.

(Example 14)
A light-reflecting molded article was produced in the same manner as in Example 13 except that coated titanium oxide B (trade name “CR-90” manufactured by Ishihara Sangyo Co., Ltd., average particle diameter of 0.25 μm) was used instead of coated titanium oxide A. did.

In addition, the surface of the rutile titanium oxide was covered with a coating layer containing aluminum oxide and silicon oxide in the coated titanium oxide B. When the amount of aluminum oxide in the coated titanium oxide B was quantified by fluorescent X-ray analysis, it was 2.7% by weight in terms of Al ₂ O ₃ with respect to the total weight of titanium dioxide. Further, when the amount of silicon oxide in the coated titanium oxide B was quantified by fluorescent X-ray analysis, it was 3.6% by weight with respect to the total weight of titanium dioxide in terms of SiO ₂ .

(Example 15)
A light-reflecting molded body was produced in the same manner as in Example 13 except that coated titanium oxide C (trade name “CR-80”, manufactured by Ishihara Sangyo Co., Ltd., average particle diameter of 0.25 μm) was used instead of coated titanium oxide A. did.

In the coated titanium oxide C, the surface of rutile type titanium oxide was coated with a coating layer containing aluminum oxide and silicon oxide. When the amount of aluminum oxide in the coated titanium oxide C was quantified by fluorescent X-ray analysis, it was 3.3% by weight in terms of Al ₂ O ₃ with respect to the total weight of titanium dioxide. Further, when the amount of silicon oxide in the coated titanium oxide C was quantified by fluorescent X-ray analysis, it was 1.8% by weight in terms of SiO ₂ with respect to the total weight of titanium dioxide.

(Example 16)
A light-reflecting molded article was produced in the same manner as in Example 13 except that coated titanium oxide D (trade name “CR-63” manufactured by Ishihara Sangyo Co., Ltd., average particle size 0.21 μm) was used instead of coated titanium oxide A. did.

In addition, as for the covering titanium oxide D, the surface of rutile type titanium oxide was coat | covered with the coating layer containing an aluminum oxide and a silicon oxide. When the amount of aluminum oxide in the coated titanium oxide D was quantified by fluorescent X-ray analysis, it was 1.4% by weight with respect to the total weight of titanium dioxide in terms of Al ₂ O ₃ . Further, when the amount of silicon oxide in the coated titanium oxide D was quantified by fluorescent X-ray analysis, it was 0.7% by weight with respect to the total weight of titanium dioxide in terms of SiO ₂ .

(Example 17)
A light-reflecting molded article was produced in the same manner as in Example 13 except that coated titanium oxide E (trade name “CR-50” manufactured by Ishihara Sangyo Co., Ltd., average particle diameter of 0.25 μm) was used instead of coated titanium oxide A. did.

In addition, as for the covering titanium oxide E, the surface of rutile type titanium oxide was coat | covered with the coating layer containing an aluminum oxide and a silicon oxide. When the amount of aluminum oxide in the coated titanium oxide E was quantified by fluorescent X-ray analysis, it was 2.3% by weight in terms of Al ₂ O ₃ with respect to the total weight of titanium dioxide. Further, when the amount of silicon oxide in the coated titanium oxide E was quantified by fluorescent X-ray analysis, it was 0.1% by weight in terms of SiO ₂ with respect to the total weight of titanium dioxide.

(Examples 18 to 22)
As shown in Table 1, the type of coated titanium oxide was changed, and in place of the benzotriazole ultraviolet absorber 1, a benzotriazole ultraviolet absorber 2 (molecular weight 447.6, trade name TINUVIN (registered trademark) manufactured by BASF) A light reflection molded article was produced in the same manner as in Example 13 except that 234) was used.

(Examples 23 and 24)
As shown in Table 1, the compounding amount of the coated titanium oxide was changed, and the benzotriazole ultraviolet absorber 2 (molecular weight 447.6, trade name TINUVIN (registered trademark) manufactured by BASF) was used instead of the benzotriazole ultraviolet absorber 1 )) Was used in the same manner as in Example 13 except that 234) was used.

(Comparative Examples 1-4)
As shown in Table 1, the type of the coated titanium oxide was changed and the coated titanium oxide was not dried by heating, the surface roughness Ra of the uneven portion 821a on the molding surface, the average interval Sm and the maximum height of the uneven portions ( A light reflector was produced in the same manner as in Example 1 except that Ry) used a male mold 82 as shown in Table 1.

(Comparative Examples 5 and 6)
As shown in Table 1, the amount of the coated titanium oxide was changed, the coated titanium oxide was not dried by heating, and the benzotriazole-based ultraviolet absorber 2 (molecular weight 447.6) was substituted for the benzotriazole-based ultraviolet absorber 1. The product name TINUVIN (registered trademark) 234) manufactured by BASF was used, and the surface roughness Ra, the average interval Sm and the maximum height (Ry) of the irregularities 821a on the molding surface were as shown in Table 1. A light reflector was manufactured in the same manner as in Example 1 except that the male mold 82 was used.

(Comparative Examples 7 to 10)
As shown in Table 2, the type of the coated titanium oxide was changed and the coated titanium oxide was not dried by heating, the surface roughness Ra of the uneven portion 821a on the molding surface, the average interval Sm and the maximum height of the uneven portions ( A light reflector was produced in the same manner as in Example 13 except that Ry) used a male die 82 as shown in Table 2.

(Comparative Examples 11 and 12)
As shown in Table 2, the amount of the coated titanium oxide was changed, the coated titanium oxide was not dried by heating, and the benzotriazole-based ultraviolet absorber 2 (molecular weight 447.6) was substituted for the benzotriazole-based ultraviolet absorber 1. The product name TINUVIN (registered trademark) 234) manufactured by BASF was used, and the surface roughness Ra, the average interval Sm and the maximum height (Ry) of the irregularities 821a on the molding surface were as shown in Table 2. A light reflector was manufactured in the same manner as in Example 13 except that the male mold 82 was used.

(Evaluation)
The average particle diameter of the coated titanium oxide contained in the light reflecting plate was measured by the method described above. The results are shown in Tables 1 and 2. Further, in the cross section along the thickness direction of the light reflecting plate, the number of coated titanium oxides having a particle diameter of 0.10 to 0.39 μm and not aggregated was measured by the method described above. The number of the coated titanium oxides was measured in 10 measurement regions arbitrarily selected from the cross section along the thickness direction of the light reflecting plate (the size of each measurement region is a square shape with a side of 30 μm). The arithmetic mean values are shown in Tables 1 and 2.

  Further, the moisture content of the coated titanium oxide contained in the light reflecting plate was also measured by the method described above. The light reflecting plate was cut to prepare 30 test pieces, and the moisture content of the coated titanium oxide was measured for each test piece according to the above method, and the arithmetic average value thereof was covered with the light reflecting plate. It was set as the water content of titanium oxide. The results are shown in Tables 1 and 2.

  Furthermore, also about the pelletized resin composition for light reflecting plate formation produced in Examples 13-24 and Comparative Examples 7-12, the moisture content of the covering titanium oxide contained in these was measured by the method mentioned above. In addition, 30 samples were prepared from the pelletized resin composition for forming a light reflector, and the moisture content of the coated titanium oxide was measured for each sample according to the above method, and the arithmetic average value was converted into pelletized light. The moisture content of the coated titanium oxide contained in the reflecting plate-forming resin composition was used. In any of the comparative examples and examples, the moisture content of the coated titanium oxide contained in the pelletized resin composition for forming a light reflecting plate and the moisture content of the coated titanium oxide contained in the light reflecting plate Was the same.

  And the light reflectance before a weather resistance test of a light reflection molding and the light reflectance after a weather resistance test were evaluated according to the following procedure, respectively. The results are shown in Tables 1 and 2. About the uneven surface of the light reflection molding, the surface roughness Ra, the average interval Sm of unevenness, the maximum height (Ry) of the uneven surface, the light reflectance and the diffuse reflectance were measured as described above. The results are shown in Tables 1 and 2.

(Weather resistance test)
A test piece having a length of 50 mm and a width of 150 mm was cut out from the light reflection plate, and an accelerated exposure test was performed on the test piece in accordance with JIS A1415 (accelerated exposure test method for plastic building materials) under the following conditions.

Irradiation device: Suga Test Instruments Co., Ltd. Trade name “Sunshine Super Long Life Weather Meter WEL-SUN-HC / B”
Irradiation conditions: Back panel temperature: 60-70 ° C., Spray spray: None Test bath temperature: 45-55 ° C., Relative humidity: 10-30%

(Light reflectance)
In the light reflectors of Examples 1 to 24 and Comparative Examples 1 to 12, before performing the accelerated exposure test, after performing the accelerated exposure test for 500 hours, and after performing the accelerated exposure test for 1000 hours The light reflectance of the piece was measured as follows. In addition, 30 test pieces were prepared and the arithmetic mean value of the light reflectivity of each test piece was made into the light reflectivity. The light reflectance was measured on the uneven surface of the test piece.

  The light reflectance of the test piece refers to the light reflectance at a wavelength of 550 nm when the total reflection light measurement is performed under the incident condition of 8 ° in accordance with the measurement method B described in JIS K7105. The absolute value when the light reflectance when using a barium sulfate plate is 100 is shown.

  Specifically, the light reflectance of the test piece is the ultraviolet-visible spectrophotometer commercially available from Shimadzu Corporation under the trade name “UV-2450” and the trade name “ISR-2200” from Shimadzu Corporation. It can be measured in combination with a commercially available integrating sphere attachment device (inner diameter: φ60 mm).

(Evaluation of uneven surface of light reflector)
About the uneven surface of the light reflection molded bodies of Examples 1 to 24 and Comparative Examples 1 to 12, the surface roughness Ra, the average interval Sm of the unevenness, and the maximum height (Ry) of the unevenness were measured as described above.

  Three flat square test pieces each having a side of 5 cm were cut out from the bottom surface portion 91 of the light reflection molded body 9 of Examples 1 to 24 and Comparative Examples 1 to 12. The surface roughness Ra of the uneven surface of each test piece was measured, and the arithmetic average value of the surface roughness Ra of the test piece was defined as the surface roughness Ra of the light reflecting molded body. The average interval Sm of the unevenness on the uneven surface of each test piece was measured, and the arithmetic average value of the average interval Sm of the unevenness on the uneven surface of the test piece was defined as the average interval Sm of the unevenness on the uneven surface of the light reflecting molded body. The maximum height (Ry) of the unevenness on the uneven surface of each test piece is measured, and the arithmetic average value of the maximum height (Ry) of the unevenness on the uneven surface of the test piece is determined as the maximum unevenness on the uneven surface of the light reflecting molded body. The height (Ry) was used. The light reflectivity of each test piece was measured, and the arithmetic average value of the light reflectivities of the test pieces was used as the light reflectivity of the light reflection molded article.

(Diffuse reflectance)
Three flat square test pieces each having a side of 5 cm were cut out from the bottom surface portion 91 of the light reflection molded body 9 of Examples 1 to 24 and Comparative Examples 1 to 12. With respect to the uneven surface of each test piece, the diffuse reflectance is measured under an incident condition of 0 ° in accordance with Measurement Method B described in JIS K7105, and the arithmetic average value of the diffuse reflectance of each test piece is reflected by light. The diffuse reflectance of the molded product was used.

  From Tables 1 and 2, the light reflection molded body of the present invention has a diffuse reflectance improved by 2.6 to 3.8% as compared with the light reflection molded body of the comparative example, and has excellent light reflection performance. I understand. For example, when the light reflection molded body of the present invention is used for a backlight of a liquid crystal display device, light incident on the light guide plate is guided after being repeatedly reflected between the front and back surfaces of the light guide plate and the light reflection molded body. Although it is led out to the front surface side of the optical plate, that is, the liquid crystal panel side, the reflection of light between the front and back surfaces of the light guide plate and the light reflection molded body is actually repeated tens of thousands of times. Therefore, although the diffuse reflectance of the light reflecting molded body of the present invention is about 2.6 to 3.8% higher than that of the comparative example, as described above, the reflection of light is repeated tens of thousands of times. In order to reach the liquid crystal panel, the difference of 2.6 to 3.8% in the diffuse reflectance of the light reflection molded body appears as a very large difference in the luminance of the liquid crystal panel. Therefore, the brightness | luminance of the display screen of a liquid crystal display device can be improved significantly by using the light reflection molded object of this invention for a backlight unit. Further, since the light derived from the back surface of the light guide plate is diffused and reflected by the uneven surface formed on the surface of the light reflection molded body so as to be uniform toward the front surface side of the light guide plate, the liquid crystal display device The brightness of the display screen can be made uniform.

  The light reflection molded body obtained by the method of manufacturing a light reflection molded body of the present invention includes, 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 illumination. It can be used by being incorporated in an illuminating device constituting a backlight of a surface lighting system such as a box, 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 Inner peripheral surface 20 Light guide plate 30 Light emission source 40 Lamp reflector 60 Case 61 Bottom face part of case 62 Peripheral wall part of case 62a Step part of case 70 Light source Body 71 Substrate 8 Mold
821a Concavity and convexity 9 Light reflection molding C Illumination body L Light emitting diode

Claims (6)

A method of manufacturing a light reflecting molded body, wherein a light reflecting molded body is manufactured by thermoforming a light reflecting plate using a mold, wherein the molding surface of the mold has an uneven portion, and the molding The surface unevenness portion has a surface roughness Ra of 1 to 20 μm and an average unevenness interval Sm of 5 to 300 μm, and is pressed against the molding surface of the mold while heating the light reflecting plate. In addition to molding along the molding surface, the concavo-convex portion of the molding surface of the mold is transferred to the surface of the light reflecting plate, the surface roughness Ra is 1 to 20 μm, and the average interval Sm of concavo-convex is 5 to 300 μm. A method for producing a light reflecting molded article, comprising producing a light reflecting molded article having an uneven surface. The method for producing a light-reflecting molded article according to claim 1, wherein the maximum height (Ry) of the irregularities of the irregularities on the molding surface of the mold is 5 to 80 µm. The method for producing a light reflecting molded article according to claim 1 or 2, wherein the light reflecting plate contains a polyolefin resin. Coated titanium oxide in which the light reflector is coated with 100 parts by weight of a polyolefin-based resin, the surface of titanium oxide is coated with a coating layer containing aluminum oxide and silicon oxide, and the water content is 0.5% by weight or less It contains 20-120 weight part, The manufacturing method of the light reflection molded object of any one of Claim 1 thru | or 3 characterized by the above-mentioned. A mold used for thermoforming a light reflecting plate, wherein a concavo-convex portion is formed on the molding surface of the mold, and the concavo-convex portion has a surface roughness Ra of 1 to 20 μm and an average interval of the concavo-convex portions. Sm is 5-300 micrometers, The metal mold | die characterized by the above-mentioned. The mold according to claim 5, wherein the maximum height (Ry) of the irregularities of the irregularities on the molding surface of the mold is 5 to 80 μm.

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