JP2010066512A - Light reflection plate and light reflection laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light reflection plate which hardly causes fall of light beam total reflectivity even when exposed to light and which can maintain excellent light beam total reflectivity over a long period of time. <P>SOLUTION: The light reflection plate is obtained by molding a polyolefin series resin composition comprising a 100 parts weight of a polyolefin series resin and 10 to 100 parts weight of covered titanium oxide in which titanium oxide surface is covered with a covering layer containing aluminum oxide and silicon oxide. In the covered titanium oxide, amount of aluminum oxide measured by fluorescent X-ray analysis is 2 to 6 wt.% to total weight of titanium dioxide when calculated in terms of Al<SB>2</SB>O<SB>3</SB>and amount of silicon oxide is 1 to 7 wt.% to total weight of titanium dioxide when calculated in terms of SiO<SB>2</SB>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light reflecting plate and a light reflecting laminated plate having a light reflecting performance excellent over a long period of time with little decrease in total light reflectance even when irradiated with light.

  In recent years, liquid crystal display devices have been used for various purposes as display devices. This liquid crystal display device is provided with a backlight unit on the back surface of the liquid crystal cell. The backlight unit includes a cold cathode tube, a lamp reflector, a light guide plate, a diffusion plate provided on the front side of the light guide plate, and The light reflecting plate is disposed on the rear surface side of the light guide plate, and the 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, or titanium oxide 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.

  In paragraphs [0057] and [0058], it is described that the inert inorganic oxide for coating the surface of titanium oxide is preferably at least one selected from the group consisting of alumina, silica and zirconia, There is a description that the surface treatment amount of the inert inorganic oxide is preferably 1 to 7% by mass with respect to the total mass of the titanium oxide after the surface treatment.

  However, as a specific example, in Example 4 of paragraph [0150], alumina, silica, and zirconia are 1% by mass, 0.5% by mass, and 0.5% by mass, respectively, with respect to the entire titanium oxide after treatment. %, The treatment amount of alumina, silica, and zirconia was very low, at or below the lower limit described in paragraph [0058].

  On the other hand, titanium oxide is activated by receiving light to generate radicals, oxidatively decompose and yellow the organic matter in contact with titanium oxide, and reduce the total light reflectance of the light reflector. There was a problem.

Further, it is known that when titanium oxide is irradiated with ultraviolet rays, it undergoes a photochemical change in the crystal and oxygen defects increase, producing purple-blue Ti ⁺³ and turning dark gray. This photochemical change is reversible and has the property of gradually restoring from dark gray to white when left in a dark place.

  And the titanium oxide used by the reflective film disclosed by patent document 1 produces the problem mentioned above, Comprising: A reflective film has the problem that a light beam total reaction rate will fall according to the use. Had.

Japanese Patent No. 4041160

  The present invention provides a light reflecting plate and a light reflecting laminated plate that maintain little excellent light total reflectance over a long period of time even when exposed to light.

The light reflecting plate of the present invention contains 100 parts by weight of a polyolefin-based resin and 10 to 100 parts by weight of coated titanium oxide in which the surface of titanium oxide is coated with a coating layer containing an oxide of aluminum and an oxide of silicon. A light reflecting plate formed by molding a polyolefin-based resin composition, wherein in the above coated titanium oxide, the amount of aluminum oxide determined by fluorescent X-ray analysis is converted to Al ₂ O ₃ and titanium dioxide 2 to 6% by weight with respect to the total weight of silicon, and the amount of silicon oxide is 1 to 7% by weight with respect to the total weight of titanium dioxide in terms of SiO ₂ .

  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.

  In addition, examples of the polypropylene resin include homopolypropylene, ethylene-propylene copolymer, propylene-α-olefin copolymer, and the like. Homopolypropylene is preferred because it does not cloud the glass plate constituting the glass. 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 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.

  Furthermore, the polyolefin resin composition contains coated titanium oxide. This coated titanium oxide is formed by coating the surface of titanium oxide with a coating layer containing a predetermined amount of aluminum oxide and silicon oxide.

  Thus, by covering the surface of titanium oxide with a coating layer containing aluminum oxide and silicon oxide in a predetermined ratio, contact between titanium oxide and polyolefin resin is avoided, and aluminum By including both the oxide of silicon and the oxide of silicon in the coating layer, the UV light incident on the titanium oxide can be largely blocked by the coating layer by the synergistic effect of both, and the oxidation of the polyolefin resin by the photocatalytic action of titanium oxide. The light reflection performance of the light reflector is controlled by preventing degradation of the polyolefin-based resin by suppressing decomposition and preventing discoloration to dark gray due to oxygen defects due to photochemical changes in the titanium oxide crystals due to ultraviolet rays. Is prevented. Titanium oxide includes a rutile type, anatase type, and ilmenite type, but a rutile type is preferable because of excellent weather resistance. The method for producing titanium oxide is not particularly limited, and examples thereof include a so-called sulfuric acid method in which a titanium sulfate solution is hydrolyzed, a so-called chlorine method in which titanium halide is vapor-phase oxidized, and the like.

In the above-mentioned coated titanium oxide, the amount of aluminum oxide quantified by fluorescent X-ray analysis converted to Al ₂ O ₃ is limited to 2 to 6% by weight with respect to the total weight of titanium dioxide in the coated titanium oxide. 2 to 5% by weight is preferable, and 2 to 4% by weight is more preferable.

In other words, in the above-mentioned coated titanium oxide, the amount of aluminum oxide quantified by fluorescent X-ray analysis converted to Al ₂ O ₃ is 100% by weight based on the total weight of titanium dioxide in the coated titanium oxide. To 2 to 6% by weight, preferably 2 to 5% by weight, more preferably 2 to 4% by weight.

  This is because when the amount of oxide of aluminum is reduced in the coating layer of the coated titanium oxide, the suppression of the photocatalytic action of the titanium oxide is insufficient, and coloring due to deterioration of the polyolefin resin occurs, and the light reflecting performance of the light reflecting plate is reduced. This is because if the amount of aluminum oxide decreases and the amount of aluminum oxide increases, the coating layer absorbs visible light, and light reflection by titanium oxide decreases, and as a result, the light reflection performance of the light reflecting plate decreases.

In the above-mentioned coated titanium oxide, the amount of silicon oxide quantified by fluorescent X-ray analysis converted to SiO ₂ is limited to 1 to 7% by weight with respect to the total weight of titanium dioxide in the coated titanium oxide. 1 to 6% by weight is preferable, and 1.5 to 5% by weight is more preferable.

In other words, in the above coated titanium oxide, the amount of silicon oxide quantified by fluorescent X-ray analysis in terms of SiO ₂ is 100% by weight based on the total weight of titanium dioxide in the coated titanium oxide. It is limited to 1 to 7% by weight, preferably 1 to 6% by weight, and more preferably 1.5 to 5% by weight.

  This is because when the amount of silicon oxide is reduced in the coating layer of the coated titanium oxide, the suppression of the photocatalytic action of the titanium oxide is insufficient, resulting in coloring due to deterioration of the polyolefin resin, and the light reflecting performance of the light reflecting plate is reduced. This is because when the amount of silicon oxide decreases and the amount of silicon oxide increases, the coating layer absorbs visible light, and light reflection by titanium oxide decreases, resulting in a decrease in light reflection performance of the light reflecting plate.

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

  If the content of the coated titanium oxide in the polyolefin-based resin composition is small, the light reflecting performance of the light reflecting plate is lowered. On the other hand, if the content is large, the light reflecting performance of the light reflecting plate is not expected to be improved. Since there exists a possibility that the lightness of a reflecting plate may fall, it is limited to 10-100 weight part with respect to 100 weight part of polyolefin resin, 20-80 weight part is preferable and 30-65 weight part is more preferable.

  Next, the manufacturing method of the said coated titanium oxide is demonstrated. In order to produce coated titanium oxide, an aqueous slurry is prepared by dispersing untreated titanium oxide in water or a medium containing water as a main component. 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 a silicon oxide on the surface of titanium oxide, a method described in JP-A-53-33228, JP-A-58-84863, or the like may be used. it can.

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

  Then, if necessary, the titanium oxide may be heated and baked to desorb crystal water from either one or both of the aluminum oxide and silicon oxide covering the titanium oxide. It should be noted that a known baking apparatus such as a rotary kiln or a tunnel kiln can be used for heating and baking the titanium oxide.

  When a water-soluble aluminum salt and a water-soluble silicate are added to an aqueous slurry, the surface of titanium oxide is coated with a coating layer containing an oxide of aluminum and an oxide of silicon according to the above-described procedure. Titanium 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 to obtain a coated titanium oxide in which the surface of titanium oxide is coated with a coating layer containing an oxide of aluminum and an oxide of silicon. Can do.

  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 airflow 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, and a ball mill, and an impact pulverizer and an attrition pulverizer are preferable. .

  Further, in order to improve the dispersibility of the coated titanium oxide in the polyolefin 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 Sangyo Co., Teika Co., Sakai Chemical Industry Co., Ltd., Furukawa Machine Metal Co., Tochem Products, Titanium Co., Ltd., Fuji Titanium Co., Ltd. , Korea Titanium Co., China Metal Processing Co., ISK Taiwan Co., Ltd. and others.

  The polyolefin resin composition may contain a primary antioxidant. This primary antioxidant is a stabilizer that traps radicals generated by heat and light and stops the radical reaction, and as such a primary antioxidant, it suppresses the decrease in the total light reflectance of the light reflector. Therefore, a phenolic antioxidant is preferable.

  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 polyolefin-based resin composition is small, the decrease in the total light reflectance of the light reflecting plate may not be suppressed, but at most, the content of the light reflecting plate There is no change in the effect of suppressing the decrease in the total light reflectivity, and the total light reflectivity of the light reflecting plate may decrease due to the coloring of the primary antioxidant itself, so 0.01% with respect to 100 parts by weight of the polyolefin resin. -0.5 weight part is preferable, 0.01-0.3 weight part is more preferable, 0.01-0.2 weight part is especially preferable.

  The polyolefin resin composition may contain a secondary antioxidant. This secondary antioxidant is designed to ionize the hydroperoxide (ROOH), which is an intermediate of auto-oxidative degradation of polyolefin resin caused by heat and light, to prevent auto-oxidation. Since the effect of suppressing the decrease in reflectance is high, phosphorus-based antioxidants and sulfur-based antioxidants are preferable, and phosphorus-based antioxidants are more preferable.

  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, and pentaerythritol tetrakis. (3-laurylthio-propionate) and the like may be mentioned, and these may be used alone or in combination of two or more.

  And, if the content of the secondary antioxidant in the polyolefin-based resin composition is small, it may not be possible to suppress the decrease in the total light reflectance of the light reflecting plate, while at most, the light reflecting plate Since there is no change in the effect of suppressing the decrease in the total light reflectance of 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the polyolefin resin, 0.01 to 0.3 parts by weight is more preferable, 0.01 to 0.2 parts by weight is particularly preferable.

  Further, the polyolefin resin composition 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 (cyphenyl) -6- (2,4-dibutoxyphenyl) -1,3-5-triazine, and effectively suppress the reduction of the total 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.

  Further, if the content of the ultraviolet absorber in the polyolefin-based resin composition is small, the decrease in the total light reflectance of the light reflecting plate cannot be suppressed, but at most, the total light reflectance of the light reflecting plate is not allowed. Since there is no change in the effect of suppressing the decrease in the amount of 0.01 to 0.5 parts by weight, more preferably 0.01 to 0.3 parts by weight, more preferably 0.01 to 0 parts by weight based on 100 parts by weight of the polyolefin resin. .2 parts by weight is particularly preferred.

  Furthermore, the hindered amine light reflection stabilizer may be contained in the polyolefin resin composition. 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. .

  Further, if the content of the hindered amine light stabilizer in the polyolefin resin composition is small, the decrease in the total light reflectance of the light reflecting plate cannot be suppressed. There is no change in the effect of suppressing the decrease in reflectivity, and the hindered amine light stabilizer itself is colored to cause a decrease in the total light reflectivity of the light reflector, so that it is 0.01-0. 5 parts by weight is preferred, 0.01 to 0.3 parts by weight is more preferred, and 0.01 to 0.2 parts by weight is particularly preferred.

  Here, the deterioration of the polyolefin-based resin is caused by cutting 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 and the molecular weight is lowered, and the polyolefin resin deteriorates. The deterioration of the polyolefin resin causes yellowing of the polyolefin resin, and as a result, the total light reflectance of the light reflecting plate is lowered.

  Therefore, in the light reflecting plate of the present invention, as described above, the coated titanium oxide formed by coating the surface of titanium oxide with a coating layer containing aluminum oxide and silicon oxide is used. In addition to avoiding contact with the resin, UV rays incident on the titanium oxide are blocked by the coating layer as much as possible to prevent oxidative degradation of the polyolefin resin due to the photocatalytic action of the titanium oxide, and in the crystal of the titanium oxide. It prevents discoloration to dark gray due to an increase in oxygen vacancies due to photochemical changes.

  Furthermore, as described above, a polyolefin-based resin composition comprising a light-reflecting plate by adding a primary antioxidant, a secondary antioxidant, an ultraviolet absorber, and a hindered amine-based light stabilizer. It is possible to further prevent a decrease in the total light reflectance of the light reflecting plate by suppressing yellowing due to deterioration of the resin and photochemical change of the coated titanium oxide.

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

  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 polyolefin-based 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 more reliably prevented, This protected UV absorber and hindered amine light stabilizer further prevent oxidative degradation of polyolefin resins by titanium oxide and suppress photochemical changes, and reduce the total light reflectance that was initially possessed. It is possible to more reliably prevent a situation where the time is lowered, and to maintain an excellent total light reflectance even over a long period of time.

  Furthermore, a copper damage inhibitor (metal deactivator) may be added to the polyolefin resin composition. By adding a copper damage inhibitor in the polyolefin-based resin composition, the light reflector comes into contact with a metal such as copper, or even when heavy metal ions such as copper ions act on the light reflector, Capable of capturing deterioration promoting factors such as copper ions as chelate compounds, even when the light reflector is in contact with metals such as copper when the light reflector is incorporated into various liquid crystal display devices or lighting devices. Further, it is possible to prevent the polyolefin 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, if the content of the copper damage inhibitor (metal deactivator) in the polyolefin-based resin composition is small, the effect of adding the copper damage inhibitor may not be manifested. Since total light reflectance may fall, 0.1-1.0 weight part is preferable with respect to 100 weight part of polyolefin resin.

  Further, an antistatic agent may be added to the polyolefin resin composition. 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 total light reflectance of the light reflecting plate can be reduced. 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. If the content of the antistatic agent excluding the polymer type antistatic agent in the polyolefin-based resin composition is small, the effect of adding the antistatic agent may not be exhibited, whereas if the content is large, the antistatic agent In addition to not being able to obtain an effect commensurate with the added concentration of the anti-static agent, the effect of the antistatic agent is reduced, or significant bleeding out, coloring and yellowing due to light may occur. The amount is preferably 0.1 to 2 parts by weight.

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

  In addition to copper damage inhibitors (metal deactivators) and antistatic agents, the polyolefin-based resin composition includes a dispersant such as a metal stearate soap, a quencher, a lactone processing stabilizer, a fluorescent whitening agent. An agent, a crystal nucleating agent, or the like may be added.

  Next, the manufacturing method of the light reflecting plate of this invention is demonstrated. This light reflecting plate is obtained by molding the polyolefin-based resin composition, and may be formed from either a foamed sheet or a non-foamed sheet.

  First, the case where the light reflecting plate of the present invention is formed from a foam sheet will be described. As a manufacturing method of this light reflector, a general-purpose method is adopted, for example, polyolefin resin and coated titanium oxide, and if necessary, primary antioxidant, secondary antioxidant, ultraviolet absorber, hindered amine light. A stabilizer and a foaming agent are supplied to an extruder and melt-kneaded to obtain a foamable polyolefin resin composition. The foamable polyolefin resin composition is extruded and foamed from a die attached to the tip of the extruder, and then from a foam sheet. The method of manufacturing the light reflection board which becomes is mentioned. The die is not particularly limited as long as it is widely used in extrusion foaming, and examples thereof include a T die and an annular die.

  In the above manufacturing method, when a T die is used as a die, a light reflecting plate made of a foamed sheet can be manufactured by extrusion foaming from a extruder into a sheet shape, while an annular die is used as a die First, a cylindrical body is manufactured by extrusion foaming from a circular die, and after the cylindrical body is gradually expanded in diameter, supplied to a cooling mandrel and cooled, the cylindrical body is moved in the extrusion direction. A light reflecting plate made of a foamed sheet can be manufactured by continuously cutting, opening and unfolding between the inner and outer peripheral surfaces.

  The blowing agent is not particularly limited, and is an organic gas such as saturated aliphatic hydrocarbons such as propane, butane and pentane, and halogenated hydrocarbons such as tetrafluoroethane, chlorodifluoroethane and difluoroethane; carbon dioxide and nitrogen gas. Gaseous inorganic compounds such as water; liquid inorganic compounds such as water; mixtures of organic acids or salts thereof with bicarbonate, such as a mixture of sodium bicarbonate and citric acid, dinitrosopentamethylenetetramine, etc. Solid foaming agents and the like are mentioned, and it is preferable to use a mixture of an organic acid or a salt thereof and bicarbonate and an organic gas, and a mixture of sodium bicarbonate and citric acid and an organic gas are used. It is more preferable to use together.

  Next, the case where the light reflecting plate is formed from a non-foamed sheet will be described. As a manufacturing method of this light reflector, a general-purpose method is adopted, for example, polyolefin resin and coated titanium oxide, and if necessary, a primary antioxidant, a secondary antioxidant, an ultraviolet absorber, and a hindered amine light. A stabilizer is supplied to an extruder and melt kneaded to obtain a polyolefin resin composition. The light reflecting plate is formed of a non-foamed sheet by extruding the polyolefin resin composition into a sheet form from a T-die attached to the tip of the extruder. The method of manufacturing is mentioned.

  Furthermore, a plurality of polyolefin resin layers are laminated and integrated, and at least one polyolefin resin layer of the polyolefin resin layers is a light-reflecting laminate formed by molding the polyolefin resin composition. Good.

  As such a light reflection laminate, for example, a polyolefin resin foam layer or a polyolefin resin non-foam layer is laminated and integrated on one surface or both surfaces of a polyolefin resin layer formed by molding the polyolefin resin composition. And a light reflection laminate.

  As a method for producing such a light-reflecting laminate, a general-purpose method is adopted. For example, (1) a foamed layer formed by molding the polyolefin-based resin composition and a non-foamed layer are co-extruded with each other. (2) A method of laminating and integrating a non-foamed layer formed by molding the polyolefin resin composition and a foamed layer by a coextrusion method, and (3) a method of laminating and integrating the polyolefin resin composition. A method of extruding and laminating a foam sheet on one or both sides of a molded non-foamed sheet, (4) a method of thermally laminating a foam sheet on one or both sides of a non-foamed sheet formed by molding the polyolefin resin composition, etc. The methods (1) and (2) above are preferred, and the feed block method is more preferred among the above (1) and (2).

  The methods (1) and (2) will be specifically described. First, as a manufacturing apparatus, two extruders, a first extruder and a second extruder, and a co-extrusion die composed of a joining die and an annular die connected to the joining die are prepared, and the first extruder and Both second extruders are connected to the confluence die of the coextrusion die.

  Then, the polyolefin resin and the foaming agent are supplied to the first extruder and melt kneaded to obtain a foamable polyolefin resin composition, while the polyolefin resin is supplied to the second extruder and in the absence of the foaming agent. To obtain a non-foaming polyolefin resin.

  When the foam layer is composed of the polyolefin resin composition, the first extruder is used. When the non-foam layer is composed of the polyolefin resin composition, the foam layer and the second extruder are used. When both non-foamed layers are composed of the polyolefin resin composition, a predetermined amount of coated titanium oxide is supplied to both the first and second extruders, and the first extruder or the second extruder is used as necessary. The secondary extruder is further fed with a primary antioxidant, a secondary antioxidant, a UV absorber and a hindered amine light stabilizer.

  Next, the foamable polyolefin-based resin composition of the first extruder and the non-foamable polyolefin-based resin of the second extruder are supplied to the merging die of the co-extrusion die and merged to form a foamable polyolefin-based resin having an annular cross section. Forming a foamable laminate comprising a composition layer and a non-foamable polyolefin resin layer laminated on one of the inner and outer surfaces of the foamable polyolefin resin composition layer, and the foamable laminate Is supplied to an annular die connected to a converging die and extruded and foamed from the annular die into a cylindrical shape to obtain a cylindrical foam.

  Subsequently, after gradually expanding the diameter of the cylindrical foam and supplying it to the cooling mandrel to cool the cylindrical foam, the cylindrical foam is continuously inserted between the inner and outer peripheral surfaces in the extrusion direction. A light formed by cutting a sheet over to form a sheet, in which two polyolefin resin layers are laminated and integrated, and one or both of the polyolefin resin layers are formed from the polyolefin resin composition. A reflective laminate can be obtained.

  The ratio of the outer diameter of the inner die at the opening of the annular die to the outer diameter of the cooling mandrel on the extruder side (outer diameter of the cooling mandrel on the extruder side / outer diameter of the inner die), so-called The blow-up ratio is preferably 2.5 to 3.5.

  In the above, two polyolefin resin layers are laminated and integrated, one or both polyolefin resin layers are formed from the polyolefin resin composition, and one polyolefin resin layer is a foam layer. In the above description, the other polyolefin-based resin layer is a non-foamed layer. However, both of the two polyolefin-based resins may be a foamed layer or a non-foamed layer. In such a case, the foaming agent may or may not be supplied to both the first extruder and the second extruder.

  Further, three or more polyolefin resin layers may be laminated and integrated, and at least one polyolefin resin layer may be a light reflecting laminate formed by molding the polyolefin resin composition. Prepare another extruder in addition to the first extruder and the second extruder, connect all the extruders to the same co-extrusion die, and then add the polyolefin resin composition to any one of the extruders. What is necessary is just to manufacture a light reflection laminated sheet by supplying and coextrusion.

  And when it is the light reflection laminated board by which several polyolefin resin layers are laminated and integrated, Comprising: At least one polyolefin resin layer is a foam layer, when the average cell diameter of a foam layer is small, a light reflector plate The unevenness formed on the surface of the light reflector is reduced, the light diffusion efficiency on the surface of the light reflector is reduced, and for example, the luminance unevenness on the surface of the backlight unit incorporating the light reflector may be increased. If it is large, the unevenness formed on the surface of the light reflecting plate becomes too large, and the total light reflectivity of the light reflecting plate may decrease, so 50 to 500 μm is preferable, 50 to 300 μm is more preferable, and 80 -200 micrometers are especially preferable. In addition, the average cell diameter of a foam layer says what was computed based on the average chord length measured based on the test method of ASTMD2842-69.

  Also, if the total thickness of the light reflecting laminate is thin, the rigidity of the light reflecting laminate may be insufficient, and the reflecting laminate may be bent. A thin-walled portion is likely to occur when forming a reflector having a shape, and if it is thick, the thickness and weight of a device incorporating the light-reflecting laminate may increase, so 0.5 to 1.5 mm is preferable.

  The light reflecting plate of the present invention can be used by being incorporated in a direct light type backlight, a sidelight type backlight, or a planar light source type backlight constituting a liquid crystal display device.

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

The light reflecting plate of the present invention contains 100 parts by weight of a polyolefin-based resin and 10 to 100 parts by weight of coated titanium oxide in which the surface of titanium oxide is coated with a coating layer containing an oxide of aluminum and an oxide of silicon. A light reflecting plate formed by molding a polyolefin-based resin composition, wherein in the above coated titanium oxide, the amount of aluminum oxide determined by fluorescent X-ray analysis is converted to Al ₂ O ₃ and titanium dioxide 2 to 6% by weight with respect to the total weight of the silicon and the amount of silicon oxide in terms of SiO ₂ is 1 to 7% by weight with respect to the total weight of titanium dioxide. Titanium oxide does not come into direct contact with the polyolefin-based resin, and the coating layer of the coated titanium oxide absorbs ultraviolet rays to substantially prevent the incidence of ultraviolet rays on the titanium oxide. The photocatalytic action of titanium fluoride is substantially suppressed. Therefore, the polyolefin-based resin is not oxidatively decomposed and colored by titanium oxide, and the light reflecting plate maintains excellent light reflecting performance over a long period of time. To do.

  In addition, the coating layer of titanium oxide generally prevents ultraviolet rays from being incident on 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.

  And in the said light reflection board, polyolefin-type resin composition is 0.01-0.5 weight part of primary antioxidant with respect to 100 weight part of polyolefin-type resin, and 0.01-0.5 of secondary antioxidant. In the case of containing parts by weight, 0.01 to 0.5 parts by weight of an ultraviolet absorber and 0.01 to 0.5 parts by weight of a hindered amine light stabilizer, a polyolefin-based polymer is used depending on the primary antioxidant and the secondary antioxidant. In addition to more reliably preventing yellowing due to deterioration of the resin, it also more reliably prevents decomposition of the UV absorber and hindered amine light stabilizer by titanium oxide, and this protected UV light The absorber and hindered amine light stabilizer more reliably prevent the oxidative decomposition of organic matter by titanium oxide and the suppression of photochemical change of titanium oxide. Bright light reflector, with never light total reflectance had initially greatly decreases in a short time, maintaining the excellent light total reflectance for a long period of time.

Example 1
Coated titanium oxide (trade name “CR-93” manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.28 μm) 50 parts by weight, homopolypropylene (trade name “PL500A” manufactured by Sun Allomer Co., Ltd.), melt flow rate: 3.3 g / 10 Min., Density: 0.9 g / cm ³ ) and 50 parts by weight were melt-kneaded at 230 ° C. in a twin screw extruder with a diameter of 30 mm to prepare a master batch A of so-called coated titanium oxide.

In the coated titanium oxide, the surface of the rutile titanium oxide was coated with a coating layer containing an aluminum oxide and a silicon oxide. When the amount of oxide of aluminum in the coated titanium 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. In addition, when the amount of silicon oxide in the coated titanium oxide was quantified by fluorescent X-ray analysis, it was 4.2% by weight based on the total weight of titanium dioxide in terms of SiO ₂ .

30 parts by weight of homopolypropylene (trade name “PL500A” manufactured by Sun Allomer Co., Ltd., melt flow rate: 3.3 g / 10 min, density: 0.9 g / cm ³ ) and 70 parts by weight of master batch A of coated titanium oxide have a diameter of 90 mm. The sheet was extruded from a T-die (sheet width: 500 mm, slit interval: 0.8 mm) that was supplied to a single-screw extruder, melted and kneaded, and attached to the tip of the extruder. The thickness was 0.2 mm and the density was A 1.3 g / cm ³ non-foamed light reflecting plate was obtained.

(Example 2)
0.1 parts by weight of a phenolic antioxidant (trade name “IRGANOX1010” manufactured by CIBA) as a primary antioxidant and 0.1 parts of a phosphorus antioxidant (trade name “IRGAFOS168” manufactured by CIBA) as a secondary antioxidant Parts by weight, 0.1 part by weight of a benzotriazole-based UV absorber (trade name “TINUVIN 326” manufactured by CIBA) as an UV absorber, and 0.1% by weight of a hindered amine light stabilizer (trade name “TINUVIN 111” manufactured by CIBA) A non-foamed light reflecting plate having a thickness of 0.2 mm and a density of 1.3 g / cm ³ was obtained in the same manner as in Example 1 except that the part was further supplied to the extruder.

(Example 3)
A tandem type extruder in which the second stage single-screw extruder (caliber: 115 mm) is connected to the tip of the first-stage single-screw extruder (caliber: 90 mm) via a connecting tube, and a single shaft having a diameter of 90 mm An extruder was prepared, and the second stage single-screw extruder of the tandem type extruder and the single-screw extruder having a diameter of 90 mm were both connected to the joining die, and an annular die was connected to the joining die.

Homopolypropylene (trade name “PF814” manufactured by Sun Allomer Co., Ltd., melt flow rate: 2.8 g / 10 min, density: 0.9 g / cm ³ ) 40 parts by weight, homopolypropylene (trade name “PL500A” manufactured by Sun Allomer Co., Ltd.), melt flow (Rate: 3.3 g / 10 min, density: 0.9 g / cm ³ ) 40 parts by weight, coated titanium oxide masterbatch containing coated titanium oxide in an ethylene-propylene block copolymer (product of Toyo Ink Co., Ltd.) Name “PPM 1KB662 WHT FD”, ethylene-propylene block copolymer: 30 wt%, coated titanium oxide: 70 wt%, 20 parts by weight, phenolic antioxidant as a primary antioxidant (trade name “IRGANOX1010 manufactured by CIBA”) ]) 0.1 parts by weight, phosphorus antioxidant as a secondary antioxidant (CIBA) 0.1 part by weight of a trade name “IRGAFOS168”), 0.1 part by weight of a benzotriazole UV absorber (trade name “TINUVIN326” manufactured by CIBA) as a UV absorber, and a hindered amine light stabilizer (product of CIBA) (Name "TINUVIN111") A polyolefin resin composition comprising 0.1 part by weight and 1.0 part by weight of a mixture of sodium bicarbonate and citric acid was supplied to the first stage extruder and melt-kneaded at 200 ° C. , 1 part by weight of butane (isobutane / normal butane (% by weight) = 35: 65) was press-fitted into the first-stage extruder and further melt-kneaded to obtain a foamable polyolefin resin composition.

In the coated titanium oxide, the surface of the rutile titanium oxide was coated with a coating layer containing an aluminum oxide and a silicon oxide. When the amount of oxide of aluminum in the coated titanium oxide 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, in the coated titanium oxide, the amount of silicon oxide was quantified by fluorescent X-ray analysis, and it was 0.7% by weight with respect to the total weight of titanium dioxide in terms of SiO ₂ .

  Subsequently, the expandable polyolefin resin composition is continuously supplied from the first-stage single-screw extruder to the second-stage single-screw extruder through the connecting pipe, and the expandable polyolefin-based resin composition is cooled to 170 ° C. After that, it was continuously fed to a confluence die attached to the tip of the second stage single screw extruder.

On the other hand, 30 parts by weight of homopolypropylene (trade name “PL500A” manufactured by Sun Allomer Co., Ltd., melt flow rate: 3.3 g / 10 min, density: 0.9 g / cm ³ ) and the master of the coated titanium oxide prepared in Example 1 70 parts by weight of batch A, 0.1 part by weight of a phenolic antioxidant (trade name “IRGANOX1010” manufactured by CIBA) as a primary antioxidant, and a phosphorus antioxidant (trade name “IRGAFOS168 manufactured by CIBA” as a secondary antioxidant) ] 0.1 parts by weight, 0.1 part by weight of a benzotriazole ultraviolet absorber (trade name “TINUVIN326” manufactured by CIBA) as an ultraviolet absorber, and a hindered amine light stabilizer (trade name “TINUVIN111” manufactured by CIBA) ) Non-foaming polyolefin resin composition comprising 0.1 parts by weight of 90 mm in diameter Confluence die attached to the tip of the extruder after having held at 200 ° C. in an extruder tip was melted and kneaded at 200 ° C. was supplied to the single screw extruder were continuously fed.

  Then, a foamable polyolefin resin composition extruded from the second single-screw extruder of the tandem extruder and a non-foamable polyolefin resin composition extruded from a single-screw extruder having a diameter of 90 mm. A non-foamable polyolefin layered on the outer surface of a foamable polyolefin resin composition layer having an annular cross-section formed of a foamable polyolefin resin composition and joined on a joining die. A foamable laminate comprising a non-foamable polyolefin resin composition layer comprising a resin-based resin composition is formed, and the foamable laminate is supplied to an annular die connected to a merging die. A cylindrical foam was obtained by extrusion foaming. In the opening of the annular die, the outer diameter of the inner die was 140 mm, and the slit interval was 0.7 mm.

Thereafter, the cylindrical foam is taken up while gradually expanding the diameter, and molded along a cylindrical cooling mandrel having a diameter of 424 mm and a length of 500 mm, in which cooling water of 25 ° C. is circulated. However, after cooling by blowing air over the entire outer peripheral surface of the cylindrical foam from the air outlet of the air ring disposed in a state surrounding the cooling mandrel, the cylindrical foam is opposed to the diametrical direction. The light reflecting laminated board in which the foamed layer was laminated and integrated on one surface of the non-foamed layer was obtained by cutting across the inner and outer peripheral surfaces at a point, and opening and developing. The obtained light reflecting laminate had an overall thickness of 0.6 mm. The non-foamed layer of the light reflecting laminate had a thickness of 0.2 mm and a density of 1.3 g / cm ³ . The foamed layer of the light reflecting laminate had a thickness of 0.4 mm and a density of 0.51 g / cm ³ .

Example 4
A coated titanium oxide masterbatch B was prepared in the same manner as in Example 1 except that coated titanium oxide (trade name “CR-90” manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) was used as the coated titanium oxide. Obtained.

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

  A light reflection comprising a foamed layer laminated and integrated on one surface of the non-foamed layer in the same manner as in Example 3 except that this coated titanium oxide masterbatch B was used in place of the coated titanium oxide masterbatch A. A laminate was obtained.

The obtained light reflecting laminate had an overall thickness of 0.6 mm. The non-foamed layer of the light reflecting laminate had a thickness of 0.2 mm and a density of 1.3 g / cm ³ . The foamed layer of the light reflecting laminate had a thickness of 0.4 mm and a density of 0.51 g / cm ³ .

(Example 5)
A coated titanium oxide masterbatch C was prepared in the same manner as in Example 1 except that coated titanium oxide (trade name “CR-80” manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) was used as the coated titanium oxide. Obtained.

In the coated titanium oxide, the surface of the rutile titanium oxide was coated with a coating layer containing an aluminum oxide and a silicon oxide. In the coating oxide in the titanium, where the amount of aluminum oxide was determined by X-ray fluorescence analysis, in terms of Al ₂ O _3, it was 3.3% by weight of the total weight of titanium dioxide. In addition, when the amount of silicon oxide in the coated titanium oxide was quantified by fluorescent X-ray analysis, it was 1.8% by weight with respect to the total weight of titanium dioxide in terms of SiO ₂ .

  A light reflection in which a foamed layer is laminated and integrated on one surface of a non-foamed layer in the same manner as in Example 3 except that this coated titanium oxide masterbatch C was used instead of the coated titanium oxide masterbatch A. A laminate was obtained.

The obtained light reflecting laminate had an overall thickness of 0.6 mm. The non-foamed layer of the light reflecting laminate had a thickness of 0.2 mm and a density of 1.3 g / cm ³ . The foamed layer of the light reflecting laminate had a thickness of 0.4 mm and a density of 0.51 g / cm ³ .

(Comparative Example 1)
A coated titanium oxide master batch D was prepared in the same manner as in Example 1 except that coated titanium oxide (trade name “CR-63” manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.21 μm) was used as the coated titanium oxide. Obtained.

In the coated titanium oxide, the surface of the rutile titanium oxide was coated with a coating layer containing an aluminum oxide and a silicon oxide. When the amount of oxide of aluminum in the coated titanium oxide 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, in the coated titanium oxide, the amount of silicon oxide was quantified by fluorescent X-ray analysis, and it was 0.7% by weight with respect to the total weight of titanium dioxide in terms of SiO ₂ .

The coated titanium oxide master batch D was used in the same manner as in Example 1 except that the coated titanium oxide master batch D was used instead of the coated titanium oxide master batch A. The non-coated titanium oxide had a thickness of 0.2 mm and a density of 1.3 g / cm ³ . A foamed light reflector was obtained.

(Comparative Example 2)
0.1 parts by weight of a phenolic antioxidant (trade name “IRGANOX1010” manufactured by CIBA) as a primary antioxidant and 0.1 parts of a phosphorus antioxidant (trade name “IRGAFOS168” manufactured by CIBA) as a secondary antioxidant Parts by weight, 0.1 part by weight of a benzotriazole-based UV absorber (trade name “TINUVIN 326” manufactured by CIBA) as an UV absorber, and 0.1% by weight of a hindered amine light stabilizer (trade name “TINUVIN 111” manufactured by CIBA) A non-foamed light reflecting plate having a thickness of 0.2 mm and a density of 1.3 g / cm ³ was obtained in the same manner as in Comparative Example 1 except that the part was further supplied to the extruder.

(Comparative Example 3)
A light-reflecting laminate in which a foamed layer is laminated and integrated on one surface of a non-foamed layer in the same manner as in Example 3 except that a masterbatch D of coated titanium oxide is used instead of the masterbatch A of coated titanium oxide. I got a plate. The obtained light reflecting laminate had an overall thickness of 0.6 mm. The non-foamed layer of the light reflecting laminate had a thickness of 0.2 mm and a density of 1.3 g / cm ³ . The foamed layer of the light reflecting laminate had a thickness of 0.4 mm and a density of 0.51 g / cm ³ .

(Comparative Example 4)
A coated titanium oxide master batch E was prepared in the same manner as in Example 1 except that coated titanium oxide (trade name “CR-50” manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) was used as the coated titanium oxide. Obtained.

In the coated titanium oxide, the surface of the rutile titanium oxide was coated with a coating layer containing an aluminum oxide and a silicon oxide. In the coating oxide in the titanium, where the amount of aluminum oxide was determined by X-ray fluorescence analysis, in terms of Al ₂ O _3, it was 2.3% by weight of the total weight of titanium dioxide. Further, in the coated titanium oxide, the amount of silicon oxide was quantified by fluorescent X-ray analysis, and it was 0.1% by weight with respect to the total weight of titanium dioxide in terms of SiO ₂ .

  A light reflection comprising a foamed layer laminated and integrated on one surface of the non-foamed layer in the same manner as in Example 3 except that this coated titanium oxide masterbatch E was used instead of the coated titanium oxide masterbatch A. A laminate was obtained.

The obtained light reflecting laminate had an overall thickness of 0.6 mm. The non-foamed layer of the light reflecting laminate had a thickness of 0.2 mm and a density of 1.3 g / cm ³ . The foamed layer of the light reflecting laminate had a thickness of 0.4 mm and a density of 0.51 g / cm ³ .

  About the obtained light reflection board and light reflection laminated board, after carrying out an accelerated exposure test for 500 hours before an accelerated exposure test, and after carrying out an accelerated exposure test for 1000 hours, a light total reflectance is measured as follows. The results are shown in Table 1.

(Accelerated exposure test)
A test piece of 50 mm in length and 150 mm in width is cut out from the light reflecting plate and the light reflecting laminated plate, and an accelerated exposure test is performed on the test piece in accordance with JIS A1415 (accelerated exposure test method for plastic building materials) under the following conditions. It was.

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

(Total light reflectance)
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 total light reflectance of the test piece was measured in the following manner. In addition, 30 test pieces were prepared for each light reflecting plate or light reflecting laminated plate, and the arithmetic average value of the light ray total reflectance of each test piece was defined as the light ray total reflectance.

  The total light reflectance of the test piece refers to the light reflectance at a wavelength of 550 nm when the total reflected light is measured under an incident condition of 8 ° in accordance with measurement method B described in JIS K7105. As an absolute value when the light reflectivity when a barium sulfate plate is used is 100.

  Specifically, the total light reflectance of the test piece was changed to the ultraviolet-visible spectrophotometer commercially available from Shimadzu Corporation under the trade name “UV-2450”, and from Shimadzu Corporation to the trade name “ISR-2200”. It can be measured in combination with a commercially available integrating sphere attachment device (inner diameter: φ 60 mm).

  In addition, when the test piece deteriorated by the accelerated exposure test and cracks or breakage occurred, the total light reflectivity could not be measured, so it was described as “breakage”.

Claims (5)

Molding a polyolefin resin composition containing 100 parts by weight of a polyolefin resin and 10 to 100 parts by weight of a coated titanium oxide whose surface is coated with a coating layer containing an aluminum oxide and a silicon oxide. In the coated titanium oxide, the amount of aluminum oxide determined by fluorescent X-ray analysis is 2 to 2 with respect to the total weight of titanium dioxide in terms of Al ₂ O ₃ . A light reflecting plate, characterized in that it is 6% by weight and the amount of silicon oxide is 1 to 7% by weight in terms of SiO ₂ with respect to the total weight of titanium dioxide. The polyolefin-based resin composition comprises 0.01 to 0.5 parts by weight of a primary antioxidant, 0.01 to 0.5 parts by weight of a secondary antioxidant and 100% by weight of a UV absorber. The light reflector according to claim 1, comprising 01 to 0.5 part by weight and hindered amine light stabilizer 0.01 to 0.5 part by weight. The light reflecting plate according to claim 1, wherein the polyolefin resin is a polypropylene resin. A light-reflecting laminate comprising a plurality of polyolefin resin layers laminated and integrated, wherein at least one polyolefin resin layer comprises 100 parts by weight of a polyolefin resin, an oxide of aluminum and a silicon oxide of titanium oxide. A polyolefin-based resin composition containing 10 to 100 parts by weight of coated titanium oxide coated with a coating layer containing a product is formed. In the coated titanium oxide, aluminum quantified by fluorescent X-ray analysis relative to the total weight of the titanium dioxide was converted amount of the oxides of is and silicon from 2 to 6% by weight relative to the total weight of the titanium dioxide was converted amount of oxides in the Al ₂ O ₃ is in the SiO ₂ 1-7 weight%, The light reflection laminated sheet characterized by the above-mentioned. At least one polyolefin resin layer of the plurality of polyolefin resin layers is a foamed layer having an average cell diameter of 50 to 500 μm and an overall thickness of 0.5 to 1.5 mm. The light reflection laminated sheet of Claim 4.