JP2018012746A - White resin composition and white molded article and white laminate comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a white resin composition that suppresses discoloration in hue or degradation in characteristics when the composition is exposed to ultraviolet light or during storage or usage.SOLUTION: The white resin composition comprises a thermoplastic resin, titanium oxide and a phenolic stabilizer. The titanium oxide includes a silica layer comprising silica and an alumina layer comprising alumina on the surface thereof, in which the content of the silica included in the silica layer and the content of the alumina included in the alumina are 0.6 to 4.5 by mass and 0.1 to 2.5 by mass, respectively, satisfying (content of alumina)<(content of silica), when the whole mass of the titanium oxide is set to 100 by mass.SELECTED DRAWING: None

Description

  The present invention relates to a white resin composition and a white molded body or a white laminated molded body comprising the white resin composition. Specifically, it can suppress discoloration and deterioration when exposed to ultraviolet light, during storage or use, and as a display base material for printing or writing, or as a liquid crystal display device, lighting fixture, or lighting signboard. The present invention relates to a white molded body or a white laminate that can be used as a reflective material used for the like, or a white resin composition that can form them.

Sheet-shaped or film-shaped white molded articles are widely used as packaging materials, image-receiving films, labels, printing base materials, etc. for the purpose of enhancing the appearance of products and improving the visibility of projected images and printed characters. Used in the field.
Further, in recent years, a sheet-shaped or film-shaped white molded article containing fine voids inside is used for liquid crystal display devices, lighting fixtures, lighting signs, etc. for the purpose of taking advantage of its excellent reflection performance and concealment performance. It is used as a reflector.
As a material for forming these white molded bodies, a white resin composition containing titanium oxide which is a high refractive index filler is used for the purpose of enhancing whiteness and hiding performance.

  The white resin composition that forms these white molded articles includes a resin composition produced when heat-molded into a sheet or film, or when the white molded article is used in harsh environments such as high temperatures. In order to suppress thermal oxidative deterioration, an antioxidant is generally blended. For example, Patent Document 1 discloses a white film containing bubbles inside formed of a resin composition comprising an antioxidant such as polyester, titanium oxide, and a hindered phenol antioxidant.

When storing or using the white molded body, it absorbs ultraviolet rays contained in sunlight, fluorescent lamps, mercury lamps and LED light to prevent color change and light deterioration, and UV absorber and / or light. It has been proposed to form a white molded body for a light reflector using a white resin composition containing a stabilizer.
For example, Patent Document 2 discloses a thermoplastic resin composition containing various antioxidants and a hindered amine light stabilizer in combination with titanium oxide as an ultraviolet light absorbing filler for the purpose of improving durability against ultraviolet light. A light reflector made of an object is disclosed.
Further, for example, Patent Document 3 discloses a light reflection comprising a polyolefin resin composition containing various antioxidants, ultraviolet absorbers, and hindered amine light stabilizers in combination with titanium oxide having a specific coating layer. The body is disclosed.

JP 2003-127305 A JP 2003-176367 A JP 2010-066652

As described above, when a white molded article containing a phenolic antioxidant is exposed to an oxidizing gas such as heat, humidity or NOx during storage or use, the phenolic compound is a colored quinone compound. Because of the change, the color sometimes changed.
In addition, in white molded products containing titanium oxide together with phenolic antioxidants, titanium oxide serves as a catalyst for the thermal oxidation reaction to change from phenolic compounds to quinone compounds, which are colored substances. There was a problem that the color tone and characteristics of the body were more likely to deteriorate over time.
Furthermore, when the white molded body has voids therein, the air in the voids promotes thermal oxidative degradation, making the color tone and characteristics of the white molded body more likely to deteriorate over time.

  Therefore, an object of the present invention relates to a white molded article containing titanium oxide together with a phenolic antioxidant, and even if it is a white molded article having voids inside, it can be stored in the atmosphere, and even a high temperature atmosphere A new white molded body capable of effectively suppressing deterioration of the color tone and characteristics of the white molded body over time even when stored under the white molded body, and a white resin composition capable of forming the white molded body It is to provide.

The present invention is a white resin composition comprising a thermoplastic resin, titanium oxide, and a phenol-based stabilizer, wherein the titanium oxide contains a silica layer containing silica on its surface and alumina. And the alumina contained in the silica layer and the alumina contained in the alumina layer are contained in the following ranges when the total mass of titanium oxide is 100 masses. A white resin composition is proposed.
Silica content: 0.6 to 4.5 mass Alumina content: 0.1 to 2.5 mass Alumina content <silica content

  The white molded body formed from the white resin composition proposed by the present invention has voids inside even if the content of silica contained in the silica layer and alumina contained in the alumina layer is within a specific range. Even if the white molded body is stored in the air or stored in a high temperature atmosphere, deterioration of the color tone and characteristics of the white molded body over time can be effectively suppressed. Therefore, for example, even when exposed to ultraviolet light for a long period of time, the photodegradation is suppressed, and the surface can be glossy and maintain high whiteness. Therefore, the white molded body formed from the white resin composition proposed by the present invention is used as, for example, a display base material for printing or writing, or as a reflective material used for liquid crystal display devices, lighting fixtures, lighting signs, and the like. It can be particularly preferably used.

It is a figure of the light resistance test which irradiates LED light. It is an adjustment figure of the titanium oxide sample for a fluorescent X ray analysis.

  Hereinafter, an example of an embodiment of the present invention will be described. However, the present invention is not limited to the embodiments described below.

<This white resin composition>
The white resin composition (referred to as “the present white resin composition”) as an example of the embodiment of the present invention is a white resin composition containing a thermoplastic resin, a phenol-based stabilizer, and titanium oxide.

<This white molded body>
Using this white resin composition, for example, the white resin composition can be molded to form various forms of white molded bodies (referred to as “present white molded bodies”).

<Thermoplastic resin>
Examples of the thermoplastic resin that can be used in the white resin composition include polyolefin resins, polyester resins, acrylic resins, polycarbonate resins, polyvinyl chloride resins, fluorine resins, polyamide resins, and polystyrene resins. A resin etc. can be mentioned, The combination of 1 type, or 2 or more types of these can be used.
Among these, a polyolefin resin, a polyester resin, or a mixed resin thereof can be cited as a preferred example in the case of stretching at least uniaxially for the purpose of containing voids in the white molded body.

  Examples of the polyolefin resin include polypropylene resins such as polypropylene and propylene-ethylene copolymers, polyethylene resins such as polyethylene, high density polyethylene, and low density polyethylene, and cycloolefins such as ethylene-cyclic olefin copolymers. And at least one polyolefin resin selected from olefin-based elastomers such as ethylene-propylene rubber (EPR) and ethylene-propylene-diene terpolymer (EPDM), one or two of these Combinations of more than one species can be used. Among these, polypropylene resin and polyethylene resin are preferable from the viewpoint of mechanical strength and flexibility, and among them, polypropylene resin is particularly preferable.

Examples of the polyester resin include at least one polyester resin selected from aliphatic polyester resins and aromatic polyester resins. You may use combining these.
Examples of the polyester resin include polylactic acid, polyethylene terephthalate, polyethylene naphthalate, polypropylene terephthalate, polybutylene terephthalate, and poly-1,4-cyclohexylenedimethylene terephthalate. Alternatively, a combination of two or more types can be used.
The polyester-based resin may be a polyester copolymer using two or more dicarboxylic acid components and / or glycol components as described above.

Examples of the polypropylene resin include polypropylene and ethylene-polypropylene copolymer. Among these, polypropylene can be preferably used.

<Phenolic stabilizer>
As a phenol type stabilizer used for this white resin composition, a phenol type antioxidant, a phenol type light stabilizer, etc. can be mentioned. Especially, it is preferable to use a phenolic antioxidant from the difference in the function mentioned later.

The phenol-based antioxidant has a function of capturing a peroxy radical generated in a thermoplastic resin under an atmosphere of heat and oxygen and suppressing an auto-oxidation reaction of the thermoplastic resin to form a white molded body. It can be mix | blended with a white resin composition.
On the other hand, phenolic light stabilizers absorb ultraviolet rays instead of thermoplastic resins, convert them into kinetic energy and heat energy that are harmless to the resin, and prevent the resin from undergoing photooxidative degradation. It can be mix | blended with a white resin composition.

(Phenolic antioxidant)
Examples of the phenolic antioxidant that can be used in the white resin composition include tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, β- (3, 5-Di-t-butyl-4-hydroxyphenyl) propionic acid stearyl ester, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene , Tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, tris [(3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxyethyl] isocyanurate, 2,6- Di-t-butyl-4-methylphenol, 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) pro Onyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5.5] undecane, ethylenebis (oxyethylene) bis [3- (5-t-butyl-hydroxy-m -Tolyl) propionate, triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate, 1,1,3-tris- (2-methyl-4-hydroxy-5-t -Butylphenyl) butane, 4,4'-butylidenebis (3-methyl-6-tert-butyl) phenol, 4,4'-thiobis (3-methyl-6-tert-butyl) phenol tris (2,6-dimethyl) -3-Hydroxy-4-t-butylbenzyl) isocyanurate can be used, and one or more of these can be used in combination. It can be.
Among them, 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} which is a semi-hindered phenolic antioxidant -2,4,8,10-tetraoxaspiro [5.5] undecane, ethylenebis (oxyethylene) bis [3- (5-t-butyl-hydroxy-m-tolyl) propionate, triethyleneglycolbis [ It is preferable to use one or a combination of two or more selected from 3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate, which exposes the white resin composition to a high temperature for a long time. However, the thermal oxidation deterioration of the white resin composition can be suppressed, and further the color change can be reduced.

  A commercially available phenolic antioxidant can be used for the white resin composition. For example Irganox1010, Irganox1035, Irganox1076, Irganox1098, Irganox1135, Irganox1330, Irganox1425WL, Irganox1520L, Irganox1726, Irganox245, Irganox259, Irganox3114, Irganox3125, Irganox3790, Irganox5057, Irganox s565, (manufactured by BASF), ADK STAB AO-20, ADK STAB AO- 30, ADK STAB AO-40, ADK STAB AO-50, ADK STAB AO-60, ADK STAB AO-70, ADK STAB AO-80 (manufactured by ADEKA), BHT (manufactured by Takeda Pharmaceutical Company Limited), CYANOX 1790 (Cyt) c Ltd.), SUMILIZER GP, SUMILIZER GM, SUMILIZER GS, and SUMILIZER GA-80, SUMILIZER WX-R (or more, can be mentioned commercial products of Sumitomo Chemical Co., Ltd.).

In the present white resin composition, when the content of the phenolic antioxidant is 0.01 parts by mass or more, it occurs when the thermoplastic resin is heat-molded or used under a severe environment such as a high temperature. It is preferable because thermal oxidative deterioration can be suppressed. On the other hand, if the content of the phenol-based antioxidant is 1 part by mass or less, it is preferable since coloring during storage and use of a molded body made of a thermoplastic resin can be suppressed.
From this viewpoint, the content of the phenolic antioxidant is preferably 0.01 parts by mass to 1 part by mass with respect to 100 parts by mass of the thermoplastic resin. More preferably, it is 5 parts by mass or less.

  In this white resin composition, a phosphorus antioxidant and a sulfur type antioxidant can be used together with a phenolic antioxidant. These are preferable because the hydroperoxide produced can be decomposed in the process of oxidizing the white resin composition containing the phenol antioxidant to prevent the start of auto-oxidation.

  Among phosphorus antioxidants and sulfur antioxidants that can be used in the white resin composition, phosphorus antioxidants are preferable, and among them, pentaerythritol-type phosphorus antioxidants are used in combination with the above phenolic antioxidants. In particular, the effect of suppressing thermal oxidative degradation is high, and coloring of the white resin composition can be suppressed, which is particularly preferable.

  Examples of the pentaerythritol-type phosphorus antioxidant include distearyl-pentaerythritol-diphosphite (manufactured by ADEKA, trade name “ADK STAB PEP-8”), bis (2,4-di-t-butylphenyl) penta. Erythritol diphosphite (manufactured by ADEKA, trade name “ADK STAB PEP-36”) and bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-diphosphite bis (2,6-si -T-butyl-4-n-octadecyloxycarbonylethyl-phenyl) pentaerythritol-diphosphite and the like can be exemplified.

(Phenolic light stabilizer)
Examples of the phenolic light stabilizer that can be used in the white resin composition include an ultraviolet absorber having a phenol structure.
Examples of the UV absorber having a phenol structure include benzotriazole UV absorbers, benzophenone UV absorbers, triazine UV absorbers, benzoate UV absorbers, and salicylate UV absorbers. One or two or more of them can be used in combination.

  Examples of the benzotriazole-based ultraviolet absorber include 2- (2-hydroxy-5-methyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-. Benzotriazole, 2- (2′-hydroxy-5′-t-butylphenyl) benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) benzotriazole, 2- (2 '-Hydroxy-3', 5'-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-t-butylphenyl) -5-chlorobenzotriazole, 2- (2H-benzo Triazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol, 2- (2′-hydroxy-3 ′, 5′-t-pe) Nylbenzotriazole, 2- [2′-hydroxy-5 ′-(1,1,3,3, -tetramethylbutyl)] benzotriazole, 2- (2′-hydroxy-3′-s-butyl-5) '-T-butylbenzotriazole, 2- (2'-hydroxy-3-dodecyl-5'-methylbenzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5 -Chlorobenzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2,2-methylenebis [4- (1,1,3,3-tetramethylbutyl)]-6- (2H- Benzotriazol-2-yl) phenol] and the like, and one or more of them can be used in combination.

  Examples of the benzophenone-based ultraviolet absorber include 2-hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone. 4-dodecyloxy-2-hydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, etc. These can be used alone or in combination of two or more.

  Examples of the triazine-based ultraviolet absorber include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(methyl) oxy] -phenol, 2- (4,6- Diphenyl-1,3,5-triazin-2-yl) -5-[(ethyl) oxy] -phenol, 2- (4,6-diphenyl-1,3,5-triazin-2-yl-[(propyl) ) Oxy] -phenol, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(butyl) oxy] -phenol, 2- (4,6-diphenyl-1, 3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol and the like can be mentioned, and one or more of these can be used in combination.

  Examples of the benzoate UV absorber include 3-hydroxyphenyl benzoate, phenylene-1,3-benzoate, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, and the like. One of these or a combination of two or more thereof can be used.

  Specific examples of the salicylate-based ultraviolet absorber include phenyl salicylate, pt-butylphenyl salicylate, p-octylphenyl salicylate, and the like. Can be used.

  A commercially available phenolic light stabilizer can be used for the white resin composition. For example, TINUVIN P, TINUVIN 234, TINUVIN 326, TINUVIN 329, TINUVIN 213, TINUVIN 571, TINUVIN 1577ED, TINUVIN 120, CHIMASSORB 81, TINUVIN PA144 (above, manufactured by BASF Corp.), Adekastab LA Tab 29, Adekastab LA Tab 29, LA-32, ADK STAB LA-36, ADK STAB LA-46, ADK STAB 1413, ADK STAB LA-F70 (manufactured by ADEKA) Viosorb 80, Viosorb 90, Viosorb 100, Viosorb 105, Viosorb 110, Viosorb 111, 130, Viosorb 111, 130 510, Viosorb 52 , Can be Viosorb 550, Viosorb 580, Viosorb 582, Viosorb 583, Viosorb 590, Viosorb 591 (or more, Kyodo Chemical Co., Ltd.) include commercially available products such as.

In the present white resin composition, the content of the phenolic light stabilizer is such that if the content of the phenolic light stabilizer is 0.01 parts by mass or more, the molded product made of a thermoplastic resin has durability against ultraviolet light. Since it can ensure, it is preferable. On the other hand, if the content of the phenolic light stabilizer is 1 part by mass or less, it is preferable since coloring during storage and use of a molded body made of a thermoplastic resin can be suppressed.
From this viewpoint, the content of the phenol-based light stabilizer is preferably 0.01 parts by mass to 1 part by mass with respect to 100 parts by mass of the thermoplastic resin. More preferably, it is 5 parts by mass or less.

<Titanium oxide>
Titanium oxide is one of the most commonly used white inorganic fillers having the highest refractive index, and has a high whiteness with a smaller amount than other white inorganic fillers such as calcium carbonate and barium sulfate. High hiding properties and high reflectivity can be imparted to the white molded body formed from the present white resin composition. In addition, by using titanium oxide, even when the thickness of the white molded body is reduced, high whiteness, high concealability, and high reflectivity can be similarly imparted.

  The titanium oxide used in the white resin composition includes a silica layer containing silica and an alumina layer containing alumina on the surface thereof, that is, the surface of particles made of titanium oxide (also referred to as “titanium oxide core particles”). Titanium oxide.

  The titanium oxide core particles are preferably rutile type titanium oxide rather than anatase type titanium oxide from the viewpoint of high whiteness and high refractive index.

Examples of the titanium oxide core particles include those manufactured industrially by the chlorine method process and those manufactured by the sulfuric acid method process.
In the chlorine method process, rutile ore containing titanium oxide as a main component is reacted with chlorine gas in a high-temperature furnace of about 1000 ° C. to produce titanium tetrachloride first, and then this titanium tetrachloride is burned with oxygen, Higher purity titanium oxide can be obtained. Therefore, in order to impart high whiteness, high concealability, and high reflectivity to the white molded body, it is preferable to use high-purity titanium oxide by a chlorine process. Titanium oxide obtained by a chlorine method process is preferable because the content of coloring elements such as vanadium, iron, copper, manganese, niobium is small, and the light absorption ability mainly in the visible light region is suppressed.
In the present invention, “high-purity titanium oxide” means titanium oxide having a low content of coloring elements such as vanadium, iron, niobium, copper, and manganese.

The silica layer on the surface of the titanium oxide core particles is preferably a layer made of silicon dioxide (SiO ₂ ). However, in this case, in addition to silicon dioxide (SiO ₂ ), for example, hydrous silicon dioxide may be included.

The alumina layer on the surface of the titanium oxide core particles is preferably a layer made of aluminum oxide (Al ₂ O ₃ ). However, in this case, in addition to aluminum oxide (Al ₂ O ₃ ), for example, hydrous aluminum hydroxide or aluminum hydroxide may be included.

  The silica layer and the alumina layer may continuously cover the entire surface of the particle surface or may be discontinuously covered, that is, there may be a portion where the silica layer and the alumina layer do not exist. However, in order to obtain a more effective effect, it is preferable to continuously and densely coat the entire particle surface side.

The titanium oxide suppresses the thermal oxidation reaction of the phenol-based compound to suppress the deterioration of the color tone and characteristics of the white molded body over time, and from the viewpoint of ensuring easy compatibility with the thermoplastic resin, from the particle surface toward the outside. Titanium oxide having a structure in which a silica layer and an alumina layer are laminated in this order is preferable.
Silica acts on the active part of the titanium oxide surface and plays a role of deactivation, while alumina plays a role of imparting affinity to the thermoplastic resin, that is, ensuring dispersibility. Since it is arranged on the titanium oxide side and the alumina layer is arranged on the thermoplastic resin side, it is a titanium oxide having a structure in which the silica layer and the alumina layer are laminated in this order from the titanium oxide particle surface to the outside. Is preferred.

When the surface of the titanium oxide is coated with an inert inorganic oxide such as alumina, silica, and zirconia, the photocatalytic activity of the titanium oxide is suppressed, and a molded article containing the titanium oxide is exposed to ultraviolet light. It is known that discoloration and deterioration of characteristics are suppressed, and so-called light resistance is improved.
However, the present inventor has found that a specific inert inorganic oxide, ie, titanium oxide in which alumina is coated in a certain amount or more, conversely impairs the effect of suppressing photocatalytic activity and contains it. It was confirmed that the light resistance of the resulting molded product might be insufficient. In response, the amount of silica that is coated in combination with the alumina is adjusted to a predetermined range, and it is found that sufficient light resistance is secured. It has been found that oxidative degradation such as thermal oxidation of the phenol-based stabilizer contained in the resin composition is suppressed, and changes in color tone and deterioration of properties of the white molded body are suppressed.

  From such a viewpoint, the ratio of the alumina mass of the alumina layer to the silica mass of the silica layer is preferably 1.1 to 1.9, more preferably 1.2 or more and 1.8 or less, and particularly 1.3. More preferably, it is 1.7 or less.

The amount of silica in the silica layer on the surface of the titanium oxide core particles is 0.6 to 4.5 mass when the total mass of titanium oxide is 100 mass, and the alumina amount in the alumina layer is the mass of silica. If it is less and less than 2.5 mass, since sufficient light resistance can be ensured for the white molded object formed from this white resin composition, it is preferable. Further, when the white molded body is stored and used, it is preferable because oxidative deterioration such as thermal oxidation of the contained phenol-based stabilizer is suppressed, and changes in color tone and deterioration of characteristics of the white molded body can be suppressed.
On the other hand, when the mass of silica in the silica layer is 0.6 mass or more when the total mass of titanium oxide is 100 mass, the oxidation such as thermal oxidation of the phenol-based stabilizer in the white molded body is suppressed. Since an effect can be ensured, it is preferable.
On the other hand, if the mass of silica is 4.5 mass or less, the dispersibility of the titanium oxide with respect to the said thermoplastic resin is securable. In addition, for example, when a polyester resin is used as the thermoplastic resin, when the resin is melted and heated such as by extrusion, hydrolysis of the resin due to moisture contained in silica is suppressed, and the appearance and physical properties of the white molded body are suppressed. Is preferable.
From this viewpoint, the amount of silica in the silica layer is 100 masses of the total mass of titanium oxide in consideration of ensuring the effect of suppressing oxidation such as thermal oxidation of the phenol-based stabilizer in the white molded body and productivity. The mass is preferably 0.6 to 4.5 mass, more preferably 1 mass or more or 4 mass or less.

When the mass of alumina in the alumina layer is less than the mass of silica and the total mass of titanium oxide is 100 mass, if the mass is 0.1 mass or more, the affinity with the thermoplastic resin is improved, Since it can disperse | distribute uniformly in a white molded object, it is preferable. On the other hand, when the mass of alumina is less than the mass of silica and the total mass of titanium oxide is 100 mass, if the mass is 2.5 mass or less, the effect of inhibiting the photocatalytic activity of titanium oxide by the coated silica is the same. It is preferable since the light resistance of the white molded body is ensured without being damaged.
From this viewpoint, the mass of alumina in the alumina layer is 0.1 to 2.5 masses when the total mass of titanium oxide is 100 masses in consideration of securing the light resistance and productivity of the white molded body. In addition, it is preferably less than the mass of the silica, more preferably 0.5 mass or more and 2.0 mass or less, and particularly preferably 1 mass or more or 1.5 mass or less.

  In this white resin composition, the masses of alumina and silica coated on the surface of titanium oxide were determined based on the results of quantifying titanium, aluminum, and silicon in the titanium oxide with a fluorescent X-ray apparatus. After converting into the ratio of an oxide, it can obtain | require as a relative value when titanium oxide is 100 mass.

As a method for forming the silica layer or the alumina layer, a surface treatment agent containing silica or aluminum may be brought into contact with the powder made of the titanium oxide core particles.
At this time, as the surface treatment agent containing silica or aluminum, for example, a surface prepared by adding a water-soluble aluminum salt or a water-soluble silicic acid salt to an aqueous slurry and adding an additive such as a dispersant as necessary. A processing agent can be mentioned. As a more preferable example, a surface treatment agent such as a silane coupling agent or an aluminum coupling agent is dispersed in an organic solvent to form a dispersion, and the dispersion is contacted with the titanium oxide core particle powder to perform the surface treatment. A method can be mentioned.
In addition, as said surface treating agent, what is necessary is just a compound which has an organic functional group and a hydrolysable group in a molecule | numerator, and what has phosphorus (P) in a side chain is especially preferable. The coupling agent having phosphorus (P) in the side chain is particularly excellent in binding property with the binder because of better compatibility with the binder.

In addition, a precursor mixture containing a silica layer or alumina layer precursor, water, and a solvent is prepared, the precursor mixture and the titanium oxide core particle powder are mixed, a sol-gel reaction is induced, and the titanium oxide core particle After coating the surface and then separating and obtaining only the particles on which the silica layer or the alumina layer has been formed by filtering, the particles may be dried and heat-treated.
Also, the powder of the composition and the titanium oxide core are mixed so that the powder of the composition constituting the silica layer or the alumina layer is mixed and the powder of the composition is melted to surround the titanium oxide core particles. After heat-treating the mixture with the particle powder, the mixture may be cooled.
In addition, it is also possible to employ a method of coating the surface of the titanium oxide core particles by a chemical vapor reaction method, a method of attaching metal compound particles, or the like.

(Organic layer)
The titanium oxide provided with the silica layer and the alumina layer may further include an organic layer in order to impart affinity with the thermoplastic resin.
As described above, dispersibility in a thermoplastic resin can be improved by forming an organic material layer made of an organic compound on the surface of titanium oxide having a silica layer and an alumina layer.
In this case, the above titanium oxide suppresses the thermal oxidation reaction of the phenol-based compound to suppress the deterioration of the color tone and characteristics of the white molded body over time, and from the viewpoint of ensuring easy compatibility with the thermoplastic resin, from the particle surface to the outside. It is preferable that it is a titanium oxide provided with the structure laminated | stacked in order of a silica layer, an alumina layer, and an organic compound layer. However, it is not limited to such a laminated structure.

Examples of the organic compound include a siloxane compound, a silane coupling agent, a polyhydric alcohol, a titanium coupling agent, an alkanolamine or a derivative thereof, and an organic compound such as a higher fatty acid or a metal salt thereof. At least one organic compound selected from the above, or a combination of two or more organic compounds can be used. Among these, siloxane compounds and silane coupling agents can be preferably used in that they can impart hydrophobicity to titanium oxide.
These organic compounds are preferable from the viewpoint of improving the hydrophobicity of titanium oxide and the affinity with the resin by physical adsorption or chemical reaction with the hydroxyl group on the titanium oxide surface.

If the amount of the organic compound layer of the organic compound layer is 0.01 mass or more when the total mass of titanium oxide is 100 mass, moisture adsorption on the titanium oxide surface is suppressed and the titanium oxide aggregates. Therefore, dispersibility is improved in the white resin composition. On the other hand, if the mass of the organic compound is 5 mass or less, the molding process of the white resin composition is stable.
From this viewpoint, the amount of the organic compound layer in the organic compound layer is preferably 0.01 to 5 mass, with 0.05 mass or more or 3 mass or less, especially when the total mass of titanium oxide is 100 mass. Of these, 0.1 mass or more or 2 mass or less is more preferred.

  The ratio of the organic compound to the total mass of titanium oxide is determined by the ratio (in percentage) of the total mass of the organic compound used for the surface treatment in the total mass of titanium oxide after the surface treatment.

(Particle size)
The average primary particle size of titanium oxide used in the white resin composition is preferably 0.1 μm to 1 μm. If the average primary particle diameter of titanium oxide is 0.1 μm or more, dispersibility in a thermoplastic resin can be secured, which is preferable. On the other hand, if the average primary particle size is 1 μm or less, it is preferable because scattering reflectivity for visible light region and near-infrared light can be secured.
From such a viewpoint, the average primary particle size of the titanium oxide is preferably 0.1 μm to 1 μm, particularly 0.15 μm or more or 0.5 μm or less, and more preferably 0.2 μm or more or 0.35 μm or less. Is more preferable.
The average primary particle size of titanium oxide can be measured by image analysis using an electron microscope.

(Titanium oxide content)
The content of titanium oxide in the white resin composition is 5 to 5% of the total mass of the white resin composition, considering the whiteness, light reflectivity, productivity, and the like required when the white molded body is obtained. It is preferable that it is 70 mass%. If the content of titanium oxide is 5% by mass or more, it is preferable because high whiteness can be imparted to the white molded body. On the other hand, when the content of titanium oxide is 70% by mass or less, the dispersibility in the thermoplastic resin can be secured, which is preferable.
From this viewpoint, the content of titanium oxide in the white resin composition is preferably 5 to 70% by mass with respect to the total mass of the white resin composition, among which 10% by mass or more and 60% by mass or less. Among these, it is more preferable that it is 20 mass% or more or 50 mass% or less.

<Other ingredients>
The white resin composition can contain other thermoplastic resins as long as the effects of the present invention are not impaired.
In addition, the white resin composition is composed of an organic filler, an inorganic filler other than titanium oxide, an antioxidant other than a phenolic antioxidant, a light stabilizer other than a phenolic light stabilizer, a heat stabilizer, a dispersant, and a fluorescent enhancement agent. Whitening agents, compatibilizers, lubricants, nucleating agents, hydrolysis inhibitors, chain extenders, and other additives can be included.

<This white molded body>
The form of the present white molded body is not particularly limited in shape, such as a film, a sheet, a plate body, and a panel body.
Moreover, the shaping | molding method as a method of forming this white molded object is not specifically limited, either. For example, it includes a molded article formed by an appropriate molding method such as extrusion molding, injection molding, vacuum heating molding, press molding, or the like.

(Void)
The white molded body may or may not contain voids inside the molded body.

  The above "does not contain voids inside the molded body" means that no voids are intentionally formed, and includes cases where voids are not intentionally formed inside the molded body. is there. As a standard of the porosity when the molded body does not contain voids, the void ratio is less than 3%, particularly less than 1%.

  The white molded body preferably contains voids in the interior from the viewpoint of ensuring high whiteness, light concealment and light reflectivity, and weight reduction. In particular, those containing voids inside the molded body have higher whiteness and concealment performance, further imparting diffuse reflectance, the subject of the present invention, namely white molding by thermal oxidation reaction of phenolic compounds This is preferable from the viewpoint that the effects of the present invention can be further enjoyed since the problem of deterioration of the color tone and characteristics of the body over time is further held.

The porosity in the case where voids are contained in the white molded body, that is, the occupation ratio of the voids in the molded body is preferably in the range of 10 to 70%. If the porosity of the white molded body is 10% or more, it is preferable because high whiteness can be secured. Moreover, if the porosity is 70% or less, it is preferable because the voids inside the white molded body are maintained in the form of closed cells, and the mechanical strength of the white molded body can be secured and the light transmittance can be suppressed. Furthermore, it is preferable because thermal oxidative deterioration due to oxygen present in the voids is suppressed.
From this viewpoint, the porosity of the white molded body is preferably in the range of 10 to 70%, more preferably 20% or more and 60% or less, and particularly preferably 30% or more and 50% or less. .

In addition, the porosity of this white molded object can be calculated | required by the following formula.
Before stretching, the density before the white molded body contains voids (referred to as “density of void-free molded body”) and after stretching, the density of the white molded body containing voids inside ( The density of the white molded body is calculated by substituting it into the following formula.
Porosity (%) = {(density of void-free molded body−density of void-containing molded body) / density of void-free molded body} × 100

As a method for containing voids in the white molded body, (1) a method in which a white resin composition is caused to contain a foaming agent and foamed by heat during extrusion or film formation, or by chemical decomposition, 2) A method in which a gas such as carbon dioxide or a vaporizable substance is added and foamed at the time of or after extrusion of the white resin composition, and (3) the white molded body is kept in a pressurized inert gas atmosphere. A method in which an active gas is contained in a white molded body, and then a white molded body containing an inert gas is heated and foamed under normal pressure. (4) A white resin composition is incompatible with a thermoplastic resin. Add, melt-extrusion, uniaxial or biaxial stretching method, (5) Add white or inorganic filler to white resin composition, melt extrusion, uniaxial or biaxial stretching method, etc. Can do.
Among these, for the white molded body, the above method (4) or (5), which allows easy control of the void size and miniaturization, can be mentioned as a preferred method.

(Thickness)
The thickness when the white molded body is plate-shaped, sheet-shaped or film-shaped is not particularly limited. As a guide, it is preferably in the range of 50 μm to 2000 μm, and more preferably in the range of 70 μm to 1000 μm, for example, considering practical handling properties.

(Light resistance)
The degree of light resistance of the white molded body can be expressed by the rate of change of the surface glossiness of the white molded body when the surface of the white molded body is irradiated with LED light under predetermined conditions.
In order to ensure light resistance, the change rate of the surface glossiness of the white molded body is preferably 2.5% or less, more preferably 1% or less. If the change rate of the surface glossiness is 2.5% or less, it can be said that the white molded body has excellent light resistance, that is, the white resin composition has excellent light resistance.

In addition, the change rate of the surface glossiness of a white molded object can be calculated | required by the following formula | equation.
Rate of change (%) = {(surface gloss before LED light irradiation−surface gloss after LED light irradiation) / surface gloss before LED light irradiation} × 100

(Discoloration prevention)
The degree of light resistance of the white molded body can be represented by a reduction width of the reflectance of the white molded body when the white molded body is stored indoors under predetermined conditions.
The reduction width of the reflectance of the white molded body is preferably 2.5% or less, and more preferably 2% or less. If the reduction width of the reflectance is 2.5% or less, the white molded body has excellent discoloration prevention properties, and the change in color tone can be suppressed even after long-term storage.
In addition, the fall width | variety of the reflectance of a white molded object can be calculated | required by the following formula | equation.

Reduction width (%) = (Reflectance at a predetermined wavelength before storage−Reflectance at the same wavelength after storage)
Here, the “predetermined wavelength” means 510 nm, and refers to a wavelength that is most affected by a discoloration phenomenon during indoor storage, so-called yellowing in a dark place.

(High temperature heat resistance)
The degree of high-temperature heat resistance of the white molded body can be represented by the reduction width of the reflectance of the white molded body when the white molded body is exposed to a high temperature atmosphere under a predetermined condition.
Specifically, it can be represented by the reduction width of the reflectance of the white molded body surface after the white molded body is exposed for 500 hours in a thermostatic chamber adjusted to 120 ° C.

  The reduction width of the reflectance of the white molded body is preferably 4% or less, and more preferably 2.5% or less. If the reduction width of the reflectance is 4% or less, the high-temperature heat resistance excellent in the white molded body is imparted, and a change in color tone can be suppressed even under severe use conditions.

In addition, the fall width | variety of the reflectance of a white molded object can be calculated | required by the following formula | equation.
Reduction width (%) = (Reflectance at a predetermined wavelength before exposure−Reflectance at the same wavelength after exposure)
Here, the “predetermined wavelength” refers to a wavelength of 440 nm and refers to a wavelength that is most affected by a discoloration phenomenon in a high temperature atmosphere.

(Long-term heat resistance)
The degree of long-term heat resistance of the white molded body can be expressed by the decrease in the reflectance of the white molded body when the white molded body is exposed to a high-temperature atmosphere under predetermined conditions.
Specifically, it can be represented by the reduction width of the reflectance of the white molded body surface after the white molded body is exposed for 1000 hr in a thermostatic chamber adjusted to 85 ° C.
The reduction width of the reflectance of the white molded body is preferably 1% or less, and more preferably 0.8% or less. If the reduction width of the reflectance is 1% or less, excellent long-term heat resistance is imparted to the white molded body, and a change in color tone can be suppressed even after a long period of use.

In addition, the fall width | variety of the reflectance of a white molded object can be calculated | required by the following formula | equation.
Reduction width (%) = (Reflectance at a predetermined wavelength before exposure−Reflectance at the same wavelength after exposure)
Here, the “predetermined wavelength” means 440 nm and refers to a wavelength that is most affected by a discoloration phenomenon in a high temperature atmosphere.

(Production method)
The method for producing the white molded body is not particularly limited, and a known method can be adopted. Below, although an example is given and demonstrated about the manufacturing method of a white molded object, it is not limited to the following manufacturing method at all.

First, titanium oxide is blended into the thermoplastic resin, and further added to the phenolic stabilizer is blended with a phosphorus antioxidant, a hindered amine light stabilizer (HALS), and other additives as necessary. This white resin composition is prepared.
Specifically, a phenolic stabilizer, a phosphorus antioxidant, a hindered amine light stabilizer (HALS), and other additives mixed as necessary with a ribbon blender, tumbler, Henschel mixer, etc. By kneading with a thermoplastic resin and titanium oxide at a temperature not lower than the melting point of the resin (for example, 180 ° C. to 250 ° C. in the case of polypropylene resin) using a Banbury mixer, a single screw or twin screw extruder, etc. A compound of the present white resin composition is obtained.
Or, a thermoplastic resin, titanium oxide, and a phenol-based stabilizer mixed with various additives as necessary, are supplied to a Banbury mixer, a single-screw or twin-screw extruder, etc. by separate feeders, etc. A compound of the white resin composition is obtained by kneading at a temperature equal to or higher than the melting point of the resin.
Alternatively, a compound in which titanium oxide, a phenol-based stabilizer, etc. are blended in a high concentration in a thermoplastic resin, a so-called master batch is prepared, and the master batch and the thermoplastic resin are mixed to have a desired composition. It can also be set as this white resin composition.

Next, after drying the white resin composition obtained as described above, the white resin composition is supplied to an extruder heated to a predetermined temperature or higher and melted by heating. When supplying this white resin composition to an extruder without drying, it is preferable to remove moisture and the like by vent suction during melt extrusion.
Thereafter, the white resin composition in a molten state is passed through a T-die for a single layer, extruded from a slit-like discharge port of the T-die, and closely adhered to a cooling roll to obtain a cast sheet.

Next, the cast sheet obtained as described above is stretched in at least a uniaxial direction as necessary. By extending | stretching, peeling arises in the interface of a thermoplastic resin and a titanium oxide in this white resin composition, and a space | gap is formed. More preferably, the cast sheet is stretched in the biaxial direction. Biaxial stretching facilitates the formation of voids and makes it easy to adjust the porosity to a preferred range.
Further, stretching in the biaxial direction is preferable because the anisotropy of the obtained white molded body is relaxed, that is, the anisotropy of the physical properties can be reduced. Moreover, the mechanical strength of the white molded body can be improved.

When the cast sheet is stretched at least in a uniaxial direction, it is preferably performed at a temperature in the range of glass transition temperature (Tg) ± 25 ° C. of the thermoplastic resin contained in the white resin composition as described above.
If the temperature at the time of stretching is set to a glass transition temperature (Tg) of −25 ° C. or more of the thermoplastic resin, the white molded body does not break at the time of stretching, and film formation can be performed stably. In addition, when the glass resin is stretched at a glass transition temperature (Tg) of + 25 ° C. or less, for example, when stretching to TD by tenter stretching, it is preferable because the porosity distribution in the width direction of the white molded body becomes uniform.

  The order of stretching when stretching in the biaxial direction is not particularly limited, and for example, simultaneous biaxial stretching or sequential biaxial stretching may be used. The obtained cast sheet may be stretched to MD by roll stretching equipment, and then supplied to a tenter equipment and stretched to TD, or biaxial stretching may be performed by tubular stretching or the like. In addition, when extending | stretching and setting it as a white molded object, it is preferable to extend | stretch in the range of 2 times or more and 10 times or less by area magnification, and it is more preferable to extend | stretch in the range of 4 times or more and 8 times or less. If it is stretched by 2 times or more, it is preferable because a void sufficient to impart high whiteness and scattering reflectivity can be formed inside the white molded body. On the other hand, stretching to 10 times or less is preferable because the mechanical strength of the white molded body is ensured and, for example, breakage in the stretching step can be prevented.

  In order to impart dimensional stability to the white molded body obtained through the stretching step, it is preferable to perform a heat setting treatment at a predetermined temperature. Moreover, although it does not restrict | limit especially about the process of a heat setting process, Since a heat setting process can be continuously performed following an extending | stretching process in a tenter equipment, it is preferable.

(Use)
The white molded body has high whiteness and can be suitably used as a display base material for printing and writing because discoloration and deterioration during storage and use are suppressed. Moreover, since it is highly reflective and discoloration and deterioration when exposed to ultraviolet light are suppressed, it can be suitably used as a reflective material for liquid crystal display devices, lighting fixtures, lighting signs, and the like.

<This white laminate>
From the viewpoint of imparting mechanical strength such as low shrinkage and folding resistance to the white molded body, a laminate ("this" formed by forming a reinforcing layer made of the resin composition A on at least one side of the white molded body. (Referred to as “white laminate”).
In this way, by laminating the reinforcing layer on at least one side of the white molded body, the white molded body plays a role of imparting high whiteness and high reflectivity, and the reinforcing layer has dimensional stability at high temperature, that is, low shrinkage. The functions can be separated so that the mechanical strength such as the property and the folding resistance is maintained, and the respective functions can be made compatible at a high level.

(Reinforcing layer)
From the viewpoint that the reinforcing layer imparts dimensional stability, particularly high temperature dimensional stability that suppresses the generation of waves and wrinkles due to heat shrinkage at high temperatures, to the white molded body and does not hinder whiteness or reflection performance. It is preferable to form the resin composition A which is superior in heat resistance to the white resin composition and which is white or transparent.

As the main component resin of the resin composition A, a thermoplastic resin may be mentioned.
Examples of the thermoplastic resin include the polyolefin resin, the polyester resin, the acrylic resin, the polycarbonate resin, the polyvinyl chloride resin, the fluorine resin, the polyamide resin, and the polystyrene, as in the white resin composition. Based resins, etc., and one or more of these can be used in combination. Among these, polyolefin resins or polyester resins can be given as preferable examples.
Further, for example, when the thermoplastic resin of the white resin composition is a polypropylene resin, a cycloolefin resin or a cyclohexane resin as a thermoplastic resin having good compatibility with the polypropylene resin and excellent in heat resistance. It is preferable to use a mixed resin of an olefin resin and a polypropylene resin as the main component resin of the resin composition.

  The glass transition temperature (Tg) of the thermoplastic resin that can be used as the main component resin of the resin composition A is preferably 100 ° C. or more and 170 ° C. or less, and particularly 110 ° C. from the viewpoint of imparting high temperature dimensional stability. More preferably, it is 160 ° C. or less, more preferably 120 ° C. or more or 150 ° C. or less.

The reinforcing layer may be a layer formed of a film-shaped molded body, or a white molded body by extrusion or coating of a molten resin composition or a solution-shaped resin composition (without forming a film). It may be a layer formed by forming a thin film thereon. When it consists of a film-form molded object, the molded object may be an unstretched state, and the molded object extended | stretched to the uniaxial direction or the biaxial direction may be sufficient as it.
Furthermore, you may bond the reinforcement layer which consists of a film-form molded object on a white molded object by providing an adhesive bond layer or an adhesive layer between white molded objects.

The white laminate can have a two-layer structure having a reinforcing layer on at least one surface of the white molded body, or a three-layer structure having A layers on both sides of the white molded body.
Moreover, it can also be set as the structure of a reinforcement layer / white molded object / white molded object / reinforcing layer which bonded together white laminated bodies.
Furthermore, it can be set as the structure of 3 or more layers which consist of a white molded object, a reinforcement layer, and resin layers B other than these.

(Thickness)
The thickness of the white laminate in the form of a plate, sheet or film is not particularly limited, but is preferably in the range of 50 μm to 2000 μm. For example, 70 μm is considered in consideration of practical handling properties. More preferably, it is in the range of ˜1000 μm.

  In the white laminate, the thickness ratio of the white molded body to the reinforcing layer (for example, when the white molded body has a reinforcing layer on both sides, the ratio of the total thickness of the reinforcing layer) is 2: 1. A range of ˜12: 1 is preferred. If the thickness ratio of the white molded body and the reinforcing layer is increased to 12: 1 or more, the thickness ratio of the reinforcing layer can be increased, and the white laminate can be imparted with good handling properties. On the other hand, if the thickness ratio of the white molded body and the reinforcing layer is increased to 2: 1 or more, the white laminate can be provided with sufficient whiteness, display visibility and light. It is preferable because it can ensure reflectivity.

<Explanation of terms>
In general, "film" refers to a thin flat product that is extremely small compared to its length and width and whose maximum thickness is arbitrarily limited, and is usually supplied in the form of a roll (Japan) Industrial standard JISK6900), and in general, “sheet” refers to a product that is thin by definition in JIS and generally has a thickness that is small instead of length and width. However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish the two in terms of the present invention, in the present invention, even when the term “film” is used, the term “sheet” is included and the term “sheet” is used. In some cases, “film” is included.

  In addition, the expression “main component” in the present specification includes the meaning of allowing other components to be contained within a range that does not hinder the function of the main component unless otherwise specified. At this time, although the content ratio of the main component is not specified, the main component (when two or more components are main components, the total amount thereof) is 50% by mass or more, preferably 70% in the composition. It occupies at least 90% by mass, particularly preferably at least 90% by mass (including 100%).

In the present invention, when expressed as “X to Y” (X and Y are arbitrary numbers), “X is preferably greater than X” and “preferably Y”, with the meaning of “X to Y” unless otherwise specified. It means “smaller”.
Further, in the present invention, when expressed as “X or more” (X is an arbitrary number), it means “preferably larger than X” unless otherwise specified, and “Y or less” (Y is an arbitrary number). ) Includes the meaning of “preferably smaller than Y” unless otherwise specified.

  In addition, when expressed as “white” in the present specification, it is not limited to being completely white, but milky white, yellowish white (cream color), red white, black white (gray), green white, blue white, brownish white , Including white, such as gold white and silver white.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples, and various applications are possible without departing from the technical idea of the present invention.

<Measurement and evaluation method>
The white resin compositions obtained in Examples / Comparative Examples, and methods for measuring and evaluating various physical properties of white molded bodies and white laminates formed therefrom will be described.
Hereinafter, the take-up (flow) direction of the molded body is indicated by MD, and the orthogonal direction thereof is indicated by TD.

(Coating amount of silica and alumina on the surface of titanium oxide (mass))
The mass of silica and alumina in the silica layer and the alumina layer formed on the surface of titanium oxide is determined from the peak height attributed to each of titanium, aluminum and silicon in the titanium oxide with the following equipment and setting conditions. After converting into the ratio of each oxide based on the result, it calculated | required as a relative value when the mass of the whole titanium oxide was 100 mass.

Apparatus: X-ray fluorescence apparatus ZSX Primus II (manufactured by Rigaku Corporation)
X-ray tube: Rh rhodium 4.0 kW
Analysis diameter: φ30
Slit: Standard Spectroscopic crystal: LiF (for titanium)
PET (for aluminum and silicon)
Detector: SC (for titanium)
PC (for aluminum and silicon)
Measurement mode: Bulk method (no balance component)
Sample thickness: 5mm
Filter: Filter HD10 (Rigaku, CatNo. RS1440M)
Thin film for analysis window: Roll sheet (Rigaku, CatNo. 3399G003)

(Surface gloss)
The surface glossiness of the white molded body was measured with the following apparatus and setting conditions.
Prior to the measurement, the apparatus was calibrated so that the glossiness of the gloss standard plate was 92.2%.

Apparatus: Multi-angle gloss meter GS-4K (manufactured by Suga Test Instruments Co., Ltd.)
Light source incident angle: 60 degrees Receiver light receiving angle: 60 degrees Glossy standard plate: Black flat optical polishing glass 2012-015-B

(Light resistance)
The light resistance of the white molded body was evaluated based on the change rate of the surface glossiness of the white molded body when the surface of the white molded body was irradiated with LED light under predetermined conditions.

  The surface of the white molded body used for the evaluation needs to have specularity, and the surface gloss is preferably 70% or more. If the surface gloss is 70% or more, the state of decomposition and degradation of the thermoplastic resin due to the photocatalytic action of titanium oxide, and consequently the change in the surface state of the white molded body, is remarkably reflected, and the light resistance can be easily evaluated. .

  An LED light source and a white molded body were set so as to satisfy the following conditions in a thermostat adjusted to 65 ° C. with respect to the white molded body, and the surface of the white molded body was irradiated with LED light. And the surface glossiness before and after irradiating was measured about the white molded object surface on the side which irradiates LED light, and the change rate of surface glossiness was calculated | required by the following formula | equation.

The measurement of the surface gloss was as described above.
Temperature in the thermostatic chamber: 65 ° C
LED light source model: White LED
Distance between LED light source and white molded product surface: 20mm
Illuminance on the surface of the white molded body: 63,000 lux Irradiation time: 500 hr

  Rate of change (%) = {(surface gloss before LED light irradiation−surface gloss after LED light irradiation) / surface gloss before LED light irradiation} × 100

The obtained change rate was evaluated in light resistance of the white molded body in light of the following evaluation criteria. However, more than Δ is a practical level.
○: Change rate ≦ 1% and light resistance is particularly excellent.
Δ: 1% <change rate ≦ 2.5% Excellent light resistance.
X: Change rate> 2.5% and light resistance is inferior.

(Porosity)
The porosity of the white molded body was determined according to the following operation.
The density before the white molded body contains voids inside before stretching (referred to as “density of void-free molded body”), and the density where the white molded body contains voids inside after stretching (Expressed as “density of void-containing molded body”) was measured and substituted into the following formula to determine the porosity (%) of the white molded body.

  Porosity (%) = {(density of void-free molded body−density of void-containing molded body) / density of void-free molded body} × 100

(Reflectance)
The reflectance of the white molded body with respect to light having a predetermined wavelength, which is necessary when evaluating the anti-discoloration property and heat resistance of the white molded body, was measured using the following apparatus and setting conditions.
Prior to the measurement, the apparatus was adjusted so that the reflectance of the standard alumina white plate was 100%, and then used for measuring the reflectance of the white molded body.

Apparatus: Spectrophotometer with integrating sphere (U-3900H, manufactured by Hitachi, Ltd.)
Standard plate: Alumina white plate Measurement wavelength range and interval: 340 nm to 800 nm, 0.5 nm

(Discoloration prevention)
The degree of discoloration prevention of the white molded body was evaluated based on the decrease in reflectance of the white molded body when stored indoors under predetermined conditions.
Specifically, after the white molded body was stored indoors under the following conditions, the reflectance of the surface of the white molded body before and after storage was measured, and the reduction width of the reflectance was determined by the following formula.
Regarding the measurement of the reflectance, the reflectance with respect to light having a wavelength of 510 nm was read and used for calculation of the decrease width in accordance with the above.

Indoor storage period: 7 days Indoor temperature: 23 ° C
Indoor lighting: Fluorescent lamp Distance between lighting fixture and white molded body: 1.5m
Illumination illuminance on the surface of the white molded body: 300 lux Illumination lighting time: 12 hr

  Decrease width (%) = (reflectance with respect to 510 nm wavelength light before storage−reflectance with respect to light having the same wavelength after storage)

The obtained width of decrease was evaluated in light of the following evaluation criteria to evaluate discoloration prevention of the white molded body. However, more than Δ is a practical level.
○: Decrease width ≦ 2% and particularly excellent in discoloration prevention.
Δ: 2% <decrease width ≦ 2.5% and excellent discoloration prevention property.
X: The width of decrease is> 2.5%, and the discoloration prevention property is inferior.

(High temperature heat resistance)
The degree of high-temperature heat resistance of the white molded body was evaluated based on the reduction width of the reflectance of the white molded body when exposed to a predetermined high-temperature atmosphere.
Specifically, after exposing the white molded body to a high temperature atmosphere in a thermostatic chamber adjusted to 120 ° C., the reflectance of the surface of the white molded body before and after exposure is measured. The reduction width of the reflectance was obtained.

Regarding the measurement of the reflectance, in accordance with the above, the reflectance with respect to light having a wavelength of 440 nm was read and used for the calculation of the decrease width.
Temperature in constant temperature bath: 120 ° C
Exposure time: 500 hr
Decrease width (%) = (reflectance for light having a wavelength of 440 nm before exposure−reflectance for light having the same wavelength after exposure)

The obtained reduced width was evaluated against the following evaluation criteria, and the high temperature heat resistance of the white molded body was evaluated. However, more than Δ is a practical level.
○: Decrease width ≦ 2.5%, and high temperature heat resistance is particularly excellent.
Δ: 2.5% <decrease width ≦ 4% and high temperature heat resistance is excellent.
X: Decrease width> 4%, and high temperature heat resistance is inferior.

(Long-term heat resistance)
The degree of long-term heat resistance of the white molded body was evaluated based on the decrease in the reflectance of the white molded body when exposed to a predetermined high temperature atmosphere.
Specifically, after exposing the white molded body to a high-temperature atmosphere in a thermostatic chamber adjusted to 85 ° C., the reflectance of the surface of the white molded body before and after the exposure is measured. The reduction width of the reflectance was obtained.

Regarding the measurement of the reflectance, in accordance with the above, the reflectance with respect to light having a wavelength of 440 nm was read and used for the calculation of the decrease width.
Temperature in the thermostatic chamber: 85 ° C
Exposure time: 1000 hr (optimization required)
Decrease width (%) = (reflectance for light having a wavelength of 440 nm before exposure−reflectance for light having the same wavelength after exposure)

The obtained reduced width was evaluated in accordance with the following evaluation criteria, and the heat resistance of the white molded body was evaluated.
However, more than Δ is a practical level.
○: Decrease width ≦ 0.8%, and heat resistance is particularly excellent.
Δ: 0.8% <decrease width ≦ 1% and excellent heat resistance.
X: Decreasing width> 1% and heat resistance is inferior.

<Example 1>
(Preparation of titanium oxide A)
After titanium oxide is vapor-phase oxidized, titanium oxide is obtained by a so-called chlorine process, the surface of the obtained titanium oxide is surface-treated with a silica-containing surface treatment agent to form a silica layer, and then an alumina-containing surface treatment agent Then, an alumina layer was formed by surface treatment with, and further an organic layer was formed by surface treatment with dimethyl silicone to obtain titanium oxide A (average primary particle size 0.3 μm). When the coating amount (mass) of silica and alumina was measured by the above-described method, it was 1.8 mass of silica and 1.3 mass of alumina.

(Preparation of white resin composition 1)
A 60:40 mass mixture of polypropylene (Novatec PP FY6HA: manufactured by Nippon Polypro Co., Ltd.) as the thermoplastic resin and titanium oxide A as the titanium oxide was prepared. Furthermore, with respect to 100 parts by mass of this mixture, phenol antioxidant A (3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl)] is used as a phenol stabilizer. Propionyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane) and phosphorus antioxidant A (bis (2,6-di-) as other additives t-butyl-4-methylphenyl) pentaerythritol-di-phosphite)) and hindered amine light stabilizer A (tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3 4-butanetetracarboxylate) at a ratio of 0.1 part by mass: 0.1 part by mass: 0.1 part by mass, and then melt-kneaded using a twin-screw extruder heated to 230 ° C. The To prepare a pellet-shaped compound of a white resin composition 1.

(Preparation of white molded body 1)
The above white resin composition 1 compound is supplied to an extruder heated to 230 ° C., melted and kneaded, extruded from a single layer T-die into a sheet, cooled and solidified on a cast roll, and a thickness of 350 μm. A sheet-like intermediate molded body was obtained. In a state where the obtained intermediate molded body is overlapped, it is sandwiched between mirror-finished SUS plates laid with a polyimide release film together with a spacer having a thickness of 1 mm, and heated and melt-pressed at 200 ° C., with a thickness of 1 mm and a 60 mm square size. A plate-shaped white molded body 1 (surface glossiness 80%) was produced. The obtained white molded body was evaluated for light resistance, and the results are shown in Table 1.

<Example 2>
(Preparation of resin composition A-1)
Pellets of cycloolefin resin A (TOPAS 6013, manufactured by Polyplastics), pellets of cycloolefin resin B (TOPAS 8007, manufactured by Polyplastics), and pellets of polypropylene (Novatech PP FY6HA: manufactured by Nippon Polypro) Of 55:20:25 was prepared. Furthermore, after blending phenolic antioxidant A and phosphorus antioxidant A at a ratio of 0.1 parts by mass to 0.1 parts by mass with respect to 100 parts by mass of this mixture, the mixture was heated to 230 ° C. The mixture was melt-kneaded using a twin-screw extruder to prepare a pellet compound of the resin composition A-1.

(Preparation of white molded body 2)
The compound of the white resin composition 1 produced in Example 1 and the compound of the resin composition A-1 were respectively supplied to the extruders A and B heated to 230 ° C., melt-kneaded, and then two types and three layers And then extruded into a sheet shape so as to have a three-layer configuration of reinforcing layer-1 / white molded body 1 / reinforcing layer-1, and solidified by cooling to obtain a sheet-like intermediate laminate. The obtained intermediate molded body was passed through a roll stretching machine adjusted to 130 ° C. and stretched 2.5 times in the MD, and then the reinforcing layer-1 on the front and back surfaces was peeled off to form a sheet-shaped white molded body having a thickness of 200 μm. 2 was obtained. The resulting white molded body 2 was evaluated for porosity and anti-discoloration property, and the results are shown in Table 2.

<Example 3>
(Preparation of white molded body 3)
The white resin composition 1 compound prepared in Example 1 was supplied to an extruder heated to 230 ° C., melt-kneaded, extruded into a sheet form from a single-layer T-die, and cooled and solidified on a cast roll. Thus, a sheet-like white molded body 3 having a thickness of 200 μm was obtained. The obtained white molded body 3 was evaluated for high heat resistance, and the results are shown in Table 3.

<Example 4>
(Preparation of white laminate 1)
After supplying the compound of the white resin composition 1 produced in Example 1 and the compound of the resin composition A-1 produced in Example 2 to the extruders A and B heated to 230 ° C., respectively, and melt-kneading Merged into a T-die for two types and three layers, extruded into a sheet shape so as to have a three-layer configuration of reinforcing layer-1 / white molded body 1 / reinforcing layer-1, cooled and solidified to form a sheet-like intermediate laminate Got. The obtained intermediate molded body was passed through a roll stretching machine controlled to 130 ° C. and stretched twice in MD, then further passed through a tenter device controlled to 140 ° C. and stretched twice in TD, and the thickness was 200 μm. A sheet-like white laminate 1 (white molded article 1: 180 μm, reinforcing layer: 10 μm, lamination ratio white molded article 1: reinforcing layer = 9: 1) was obtained. The resulting white laminate 1 was evaluated for porosity and long-term heat resistance, and the results are shown in Table 4.
Regarding the porosity, assuming that there was no void inside the reinforcing layer, the porosity of the white molded body was calculated from the porosity of the entire laminate, and this was used as the porosity (%) of the white laminate 1.

<Example 5>
(Preparation of titanium oxide B)
Titanium oxide is obtained by a chlorine method process that vapor-phase oxidizes titanium halide, and the surface of the obtained titanium oxide is surface treated with a silica-containing surface treatment agent to form a silica layer, and then the surface is treated with an alumina-containing surface treatment agent. After the treatment to form an alumina layer, a surface treatment was further performed with dimethyl silicone to form an organic layer, and titanium oxide B (average primary particle size 0.25 μm) was obtained. When the coating amount (mass) of silica and alumina was measured by the above method, it was 1.7 mass of silica and 1.0 mass of alumina.

(Preparation of white resin composition 2)
In the production of the white resin composition 1 of Example 1, a pellet-like compound of the white resin composition 2 was produced in the same manner as in Example 1 except that titanium oxide B was used as titanium oxide.

(Preparation of white molded body 4)
In the production of the white molded body 1 of Example 1, the white molded body 2 (surface) was obtained in the same manner as in Example 1 except that the compound of the white resin composition 2 was used instead of the compound of the white resin composition 1. (Glossiness 77%). The obtained white molded body 2 was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

<Comparative Example 1>
(Production of titanium oxide C)
Titanium oxide is obtained by a chlorine process that vapor-phase oxidizes titanium halide, and the surface of the obtained titanium oxide is surface treated with an alumina-containing surface treatment agent to form an alumina layer, and then surface treated with dimethyl silicone. Thus, an organic layer was formed, and titanium oxide C (average primary particle size 0.25 μm) was obtained. When the coating amounts (mass) of silica and alumina were measured by the above-described method, they were 0 mass for silica and 1.1 mass for alumina.

(Preparation of white resin composition 3)
In the production of the white resin composition 1 of Example 1, a pellet-like compound of the white resin composition 3 was produced in the same manner as in Example 1 except that titanium oxide C) was used as titanium oxide.

(Preparation of white molded body 5)
In the production of the white molded body 1 of Example 1, the white molded body 5 (surface) was obtained in the same manner as in Example 1 except that the compound of the white resin composition 3 was used instead of the compound of the white resin composition 1. (Glossiness 88%). About the obtained white molded object 5, evaluation similar to Example 1 was performed, and the result was shown in Table 1.

<Comparative example 2>
(Preparation of white resin composition 4)
In the production of the white resin composition 1 of Example 1, except that titanium oxide C (average primary particle size 0.25 μm, silica 1.0 mass, alumina 1.0 mass) was used as the titanium oxide. In the same manner as in Example 1, a pellet-like compound of the white resin composition 4 was produced.

(Preparation of white molded body 6)
In the production of the white molded body 1 of Example 1, the white molded body 6 was produced in the same manner as in Example 1 except that the compound of the white resin composition 4 was used instead of the compound of the white resin composition 1. did. The obtained white molded body 6 (surface glossiness 74%) was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

<Comparative Example 3>
(Production of titanium oxide D)
Titanium oxide is obtained by a chlorine method process that vapor-phase oxidizes titanium halide, and the surface of the obtained titanium oxide is surface treated with a silica-containing surface treatment agent to form a silica layer, and then the surface is treated with an alumina-containing surface treatment agent. After the treatment to form an alumina layer, a surface treatment was further performed with dimethyl silicone to form an organic layer, and titanium oxide D (average primary particle size 0.25 μm) was obtained. When the coating amount (mass) of silica and alumina was measured by the above method, it was 0.2 mass of silica and 0.7 mass of alumina.

(Preparation of white resin composition 5)
In the production of the white resin composition 1 of Example 1, except that the titanium oxide D (average primary particle size 0.25 μm, silica 0.2 mass, alumina 0.7 mass) was used as the titanium oxide, the example In the same manner as in Example 1, a pellet-like compound of the white resin composition 5 was produced.

(Preparation of white molded body 7)
In the production of the white molded body 1 of Example 1, a white molded body 7 (surface) was obtained in the same manner as in Example 1 except that the compound of white resin composition 5 was used instead of the compound of white resin composition 1. (Glossiness 91%). About the obtained white molded object 7, evaluation similar to Example 1 was performed, and the result was shown in Table 1.
It was.

<Comparative Example 4>
(Preparation of white molded body 8)
In the production of the white molded body 2 of Example 2, a white molded body 8 was produced in the same manner as in Example 2, except that the compound of the white resin composition 5 was used instead of the compound of the white resin composition 1. did. About the obtained white molded object 8, the porosity and discoloration prevention property were evaluated similarly to Example 2, and the result was shown in Table 2.

<Comparative Example 5>
(Preparation of white molded body 9)
In the production of the white molded body 3 of Example 3, the white molded body 9 was produced in the same manner as in Example 3 except that the compound of the white resin composition 3 was used instead of the compound of the white resin composition 1. did. About the obtained white molded object 9, high heat resistance evaluation was performed similarly to Example 3, and the result was shown in Table 3.

<Comparative Example 6>
(Preparation of white laminate 2)
In the production of the white laminate 1 of Example 4, the white laminate 2 was produced in the same manner as in Example 4 except that the compound of the white resin composition 5 was used instead of the compound of the white resin composition 1. did. About the obtained white laminated body 2, the porosity and long-term heat resistance were evaluated similarly to Example 4, and the result was shown in Table 4.

As is clear from Tables 1 to 4, the white molded body and the white laminate made of the white resin composition of Examples 1 to 5 have excellent light resistance, anti-discoloration property, high temperature heat resistance, and long-term heat resistance. It has been found that changes in color tone and deterioration of characteristics can be suppressed when exposed to ultraviolet light such as an LED light source, during storage, and when used at high temperatures.
Among them, in the white molded body containing no voids in Examples 1 and 5, including the influence of the photocatalytic action generated on the titanium oxide surface, the deterioration of the thermoplastic resin in contact therewith is suppressed, and the decrease in glossiness is suppressed. Since it was possible, it turned out that it is a white resin composition provided with the outstanding light resistance.
Further, even in the white molded body containing voids in Example 2, the deterioration of the thermoplastic resin and the phenol-based stabilizer, including the influence of the oxidizing action by oxygen present in the voids, is suppressed, and the color tone From this, it was found that the white resin composition had excellent discoloration prevention properties.
On the other hand, the white molded bodies and white laminates made of the white resin compositions of Comparative Examples 1 to 6 are inferior in light resistance, discoloration prevention property, high-temperature heat resistance, and long-term heat resistance, and have not reached a practical level. I understood.

  From the above examples and the results of tests conducted by the inventor so far, the present inventor, on the other hand, in the case of titanium oxide in which a specific inert inorganic oxide, that is, alumina is coated with a certain amount or more, It was confirmed that the effect of suppressing the photocatalytic activity was impaired, and the light resistance of a molded product containing the same might be insufficient. In response, the amount of silica that is coated in combination with the alumina is adjusted to a predetermined range, and it is found that sufficient light resistance is secured. It has been found that oxidative degradation such as thermal oxidation of the phenol-based stabilizer contained in the resin composition is suppressed, and changes in color tone and deterioration of properties of the white molded body are suppressed.

  From such a point of view, the white resin composition containing a thermoplastic resin, titanium oxide, and a phenol-based stabilizer contains, as the titanium oxide, a silica layer containing at least silica and alumina on the surface thereof. When the content of silica contained in the silica layer and alumina contained in the alumina layer is 100 mass of the total mass of titanium oxide, the content of silica: 0.6 -4.5 mass, alumina content: 0.1-2.5 mass, and it is preferable to use titanium oxide with alumina content <silica content. If a white molded body is formed from the white resin composition contained, even if it is a white molded body with voids inside, it can be stored in the atmosphere, It is stored and can be thought of as can be effectively suppressed deterioration with time of the color tone and properties of the white moldings.

Claims (11)

A white resin composition comprising a thermoplastic resin, titanium oxide, and a phenol-based stabilizer, wherein the titanium oxide has a silica layer containing silica and an alumina layer containing alumina on the surface thereof. And the contents of the silica contained in the silica layer and the alumina contained in the alumina layer are contained in the following ranges, respectively, when the total mass of titanium oxide is 100 masses. White resin composition.
Silica content: 0.6 to 4.5 mass Alumina content: 0.1 to 2.5 mass Alumina content <silica content   2. The white resin composition according to claim 1, wherein the titanium oxide is a titanium oxide having a configuration in which a silica layer and an alumina layer are laminated in this order from the particle surface toward the outside.   The white titanium oxide according to claim 1 or 2, wherein the titanium oxide is titanium oxide having a configuration in which a silica layer, an alumina layer, and an organic compound layer are laminated in this order from the particle surface toward the outside. Resin composition.   The white resin composition according to any one of claims 1 to 3, wherein the titanium oxide has a ratio of silica content to alumina content of 1.1 to 1.9.   The white resin composition according to any one of claims 1 to 4, wherein the phenol-based stabilizer is a phenol-based antioxidant, a phenol-based light stabilizer, or a combination of both.   The white resin composition according to claim 1, wherein the thermoplastic resin is a polyolefin resin.   The white molded object which has the white resin composition in any one of Claims 1-6.   The change rate of the surface glossiness is 2.5% or less before and after the durability test in which the LED light is irradiated for 500 hours in a thermostatic chamber adjusted to 65 ° C. White molded body.   The white molded body according to claim 7 or 8, wherein voids are contained inside the molded body.   A method for producing a white molded body, comprising forming the white resin composition according to any one of claims 1 to 6 and then stretching in a uniaxial or biaxial direction to form voids in the molded body. The white lamination molded object provided with the reinforcing layer in the front-and-back one side or both sides of the white molded object in any one of Claims 7-9.

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