Resin composition and molded article comprising same

Abstract

To provide a resin composition having good concealability in a visible light region, and to provide a molded article containing the same.SOLUTION: The resin composition contains the thermoplastic resin and the inorganic powder at a mass ratio of 10:90 to 80:20. The amount of silicon element in the inorganic powder is 0.05% by mass or more and 1.00% by mass or less. The amount of aluminum element in the inorganic powder is 0.03 mass% or more and 0.40 mass% or less. The amount of an iron element in the inorganic powder is 0.03 mass% or more and 0.40 mass% or less. The amount of magnesium element in the inorganic powder is 0.02% by mass or more and 0.50% by mass or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition and a molded article containing the same. [Background technology]

[0002] Conventionally, resin compositions in which inorganic powder such as calcium carbonate powder is filled into a thermoplastic resin have been known (see, for example, Patent Document 1). Molded articles of such resin compositions can use less resin than molded articles of resin compositions that do not contain inorganic powder, and can reduce the environmental impact, and therefore are used in a wide range of applications, such as synthetic paper, daily necessities, packaging materials, food containers, cosmetic containers, automotive parts, building materials, home appliances, and optical design parts.

[0003] Among these applications, for example, high hiding power in the visible light region may be required for applications such as packaging materials, cosmetic containers, and housings for home appliances. In such cases, thermoplastic resin compositions are usually provided with hiding power in the visible light region using dyes or pigments (hereinafter also referred to as "pigments, etc.") (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-77472 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-219548 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even if an attempt is made to incorporate a pigment or the like into a resin composition, the pigment or the like is difficult to disperse in the resin composition, which is a factor that reduces production efficiency, and if the pigment or the like becomes non-uniformly dispersed in the resin composition, it is a factor that causes variations in shielding properties.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resin composition having good hiding power in the visible light region, and a molded article containing the same. [Means for solving the problem]

[0007] The present invention relates to the following resin composition and molded article.

[0008] [1] A thermoplastic resin and an inorganic powder are contained in a mass ratio of 10:90 to 80:20, The amount of silicon element in the inorganic powder is 0.05% by mass or more and 1.00% by mass or less, The amount of aluminum element in the inorganic powder is 0.03% by mass or more and 0.40% by mass or less, The amount of iron element in the inorganic powder is 0.03% by mass or more and 0.40% by mass or less, The amount of magnesium element in the inorganic powder is 0.02% by mass or more and 0.50% by mass or less. Resin composition.

[0009] [2] The amount of silicon element in the inorganic powder is 0.08% by mass or more and 0.70% by mass or less, The amount of aluminum element in the inorganic powder is 0.06% by mass or more and 0.35% by mass or less, The amount of iron element in the inorganic powder is 0.06% by mass or more and 0.35% by mass or less, The amount of magnesium element in the inorganic powder is 0.05% by mass or more and 0.40% by mass or less. The resin composition according to [1].

[0010] [3] The thermoplastic resin includes a polypropylene-based resin and / or a polyethylene-based resin. The resin composition according to [1] or [2].

[0011] [4] The inorganic powder is calcium carbonate powder. The resin composition according to any one of [1] to [3].

[0012] [5] The calcium carbonate powder includes calcium carbonate powder made from at least one material selected from the group consisting of carbide slag, waste gypsum, coal ash, and incineration ash, [4] The resin composition according to [4].

[0013] [6] The average particle size of the calcium carbonate powder measured by an air permeability method in accordance with JIS M 8511:2014 is 0.7 μm or more and 10.0 μm or less; [4] or [5]. The resin composition according to [4] or [5].

[0014] [7] The thermoplastic resin and the inorganic powder are contained in a mass ratio of 25:75 to 75:25. The resin composition according to any one of [1] to [6].

[0015] [8] A molded article comprising the resin composition according to any one of [1] to [7].

[0016] [9] The molded article according to [8], wherein the resin composition constituting the molded article has voids inside.

[0017]

[10] Measured density ρ of the molded product m and the theoretical density ρ of the molded product t and satisfy the relationship of the following formula (I): [9] The molded product according to the present invention. Formula (I) ρ m ≦0.80ρ t (In the formula, the theoretical density ρ t indicates the density when the molded product has no voids.) [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a resin composition having good hiding power in the visible light region, and a molded article containing the same. [Brief explanation of the drawings]

[0019] [Figure 1]FIG. 1 shows the optical spectra of the molded bodies of Examples 2 and 7 and Comparative Example 1 in the visible light region. DETAILED DESCRIPTION OF THE INVENTION

[0020] It is known that inorganic powders usually contain trace elements derived from the raw materials or their synthesis process. In order to make the most of the inherent properties of the inorganic powders, such trace elements are often used after being reduced to or removed from a predetermined amount.

[0021] The present inventors have conducted extensive research focusing on these trace elements and have found that resin compositions using inorganic powders containing silicon, aluminum, iron, and magnesium in amounts greater than or equal to a predetermined amount as trace elements absorb visible light more strongly over a broad range than resin compositions using inorganic powders containing almost no of these elements. This has led to the discovery that resin compositions can be imparted with visible light hiding properties without the use of pigments or the like. While the reason for this is unclear, it is believed that the oxides or carbonates of silicon, aluminum, iron, and magnesium present in or on the surface of the polycrystalline inorganic powder strongly absorb visible light.

[0022] On the other hand, if the amount of these elements in the inorganic powder is too high, the appearance of the molded product is likely to be damaged due to coloration of the inorganic powder, the strength of the molded product is likely to decrease due to oxidative degradation of the resin over time, and the hardness of the inorganic powder increases excessively, making the molding machine more susceptible to wear.In contrast, it has been found that these problems can be suppressed by keeping the amount of these elements in the inorganic powder below a specified amount.

[0023] Hereinafter, one embodiment of the present invention will be described in detail. However, the present invention is not limited to this embodiment. Furthermore, in this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the lower and upper limits.

[0024] 1.Resin composition The resin composition according to this embodiment contains a thermoplastic resin and an inorganic powder in a mass ratio of 10:90 to 80:20, and the inorganic powder satisfies the following (Requirement 1) to (Requirement 4). (Requirement 1) The amount of silicon element in the inorganic powder is 0.05% by mass or more and 1.00% by mass or less (Requirement 2) The amount of aluminum element in the inorganic powder is 0.03% by mass or more and 0.40% by mass or less (Requirement 3) The amount of iron element in the inorganic powder is 0.03% by mass or more and 0.40% by mass or less (Requirement 4) The amount of magnesium element in the inorganic powder is 0.02% by mass or more and 0.50% by mass or less

[0025] The mass ratio of the thermoplastic resin to the inorganic powder contained in the resin composition is 10:90 to 80:20 (mass ratio), and preferably 25:75 to 75:25 (mass ratio). By setting the mass ratio of the thermoplastic resin to the inorganic powder within the above range, the amount of resin can be reduced, and a resin composition with a lower environmental impact can be obtained.

[0026] 1-1.Thermoplastic resin The thermoplastic resin preferably contains a polyolefin resin as a main component. The amount of the polyolefin resin in the thermoplastic resin is, for example, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The thermoplastic resin may contain only one type of polyolefin resin, or may contain two or more types.

[0027] A polyolefin resin is a resin whose main component is an olefin-derived structural unit. In the present application, a polyolefin resin is a resin in which the amount of olefin-derived structural units relative to all structural units constituting the polyolefin resin is 50% by mass or more. A polyolefin resin may be a homopolymer of one type of olefin, a copolymer of two or more types of olefins, or a copolymer of one or more types of olefins and one or more other monomers (monomers other than olefins). The amount of olefin-derived structural units in the polyolefin resin is preferably 75% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more.

[0028] Examples of olefins include ethylene and α-olefins having 3 to 10 carbon atoms. Specific examples of olefins include ethylene, propylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene, 1-heptene, 4-methylpentene-1, 3-methyl-1-hexene, and 1-octene. Polyolefin resins may contain only one type of structural unit derived from these, or may contain two or more types.

[0029] Examples of other monomers include diene monomers such as 1,4-hexadiene, 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, dicyclopentadiene (DCPD), ethylidene norbornene (ENB), norbornadiene, and 5-vinyl-2-norbornene; acid (or acid anhydride)-modified olefins such as maleic anhydride-modified olefins; and (meth)acrylates such as methyl (meth)acrylate. The polyolefin resin may contain only one type of structural unit derived from these, or may contain two or more types.

[0030] The polyolefin resin preferably contains at least one of a polypropylene resin and a polyethylene resin. The polypropylene resin and the polyethylene resin may be virgin resin, recycled resin, or a mixture thereof.

[0031] In this specification, the term "polypropylene resin" refers to a resin containing 50% by mass or more of structural units derived from propylene, and includes propylene homopolymers and copolymers of propylene with other monomers (propylene copolymers). Propylene homopolymers include isotactic, syndiotactic, atactic, hemiisotactic, and linear or branched polypropylenes exhibiting various stereoregularities. The stereoregularity of propylene is 13 The propylene copolymer can be identified by C-NMR or the like. The propylene copolymer may be a random copolymer or a block copolymer. The propylene copolymer may be a binary copolymer of propylene and another monomer, or a multi-component copolymer of propylene and two or more other monomers. Examples of preferred copolymerization components (other monomers) include ethylene, α-olefins having 4 or more carbon atoms, tetrafluoroethylene, vinyl acetate, etc. In this embodiment, the polypropylene-based resin is preferably a propylene homopolymer or a propylene copolymer containing less than 5 mass% of structural units derived from other monomers.

[0032] In this specification, the term "polyethylene-based resin" refers to a resin containing 50% by mass or more of structural units derived from ethylene, and includes ethylene homopolymers and copolymers of ethylene and other monomers (ethylene copolymers). Examples of ethylene homopolymers include high-density polyethylene (HDPE), low-density polyethylene (LDPE), medium-density polyethylene, and linear low-density polyethylene (LLDPE). The ethylene copolymer may be a binary copolymer of ethylene and other monomers, or a multi-component copolymer of ethylene and two or more other monomers. Examples of preferred copolymerization components (other monomers) include vinyl acetate and α-olefins having 3 or more carbon atoms. In this embodiment, the polyethylene-based resin is preferably an ethylene homopolymer or an ethylene copolymer containing less than 5% by mass of structural units derived from other monomers.

[0033] The thermoplastic resin may further include a resin other than the polyolefin-based resin, as described above. Examples of the resin other than the polyolefin-based resin include thermoplastic resins such as poly(meth)acrylic acid (ester), polyvinyl acetate, polyacrylonitrile, polystyrene, ABS resin, polycarbonate, polyamide, polyvinyl alcohol, petroleum hydrocarbon resin, and coumarone-indene resin; and elastomers such as styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-butadiene-ethylene copolymer, styrene-isoprene-ethylene copolymer, acrylonitrile-butadiene copolymer, and fluorine-based elastomer.

[0034] The content of the thermoplastic resin in the resin composition is not particularly limited, but is preferably 5% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 75% by mass or less, and even more preferably 30% by mass or more and 65% by mass or less, relative to the total amount of the resin composition. When the content of the thermoplastic resin is equal to or greater than the lower limit, the proportion of inorganic powder does not become too high, which can improve the molding processability and the appearance of the molded product. When the content of the thermoplastic resin is equal to or less than the upper limit, not only can the environmental load be reduced, but the proportion of inorganic powder does not become too low, which can increase the mechanical strength.

[0035] 1-2.Inorganic powder The inorganic powder is a powder made of an inorganic substance. The type of inorganic substance can be selected depending on the application of the resin composition. Examples of inorganic substances include carbonates, silicates, phosphates, borates, oxides, sulfates, and hydrates of calcium, magnesium, aluminum, titanium, iron, zinc, silicon, barium, molybdenum, sodium, and potassium. Examples of inorganic substances also include inorganic carbon compounds.

[0036] Specific examples of inorganic substances include calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, silica, alumina, clay (e.g., talc, kaolin, etc.), aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate, aluminum sulfate, magnesium sulfate, calcium sulfate, magnesium phosphate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium sulfite, sodium sulfate, potassium titanate, bentonite, wollastonite, dolomite, graphite, etc. These may be synthetic or made from natural minerals. The inorganic powder may contain only one of these or two or more.

[0037] Preferred examples of inorganic powders include calcium carbonate, magnesium carbonate, dolomite, zinc oxide, titanium oxide, silica, alumina, clay, talc, kaolin, calcium sulfate, aluminum hydroxide, and magnesium hydroxide powders, with calcium carbonate powder being particularly preferred.

[0038] The calcium carbonate may be so-called light calcium carbonate, which is prepared by a synthetic method, or so-called heavy calcium carbonate, which is obtained by mechanically crushing and classifying a natural raw material containing CaCO as a main component, such as limestone, or a mixture thereof. Among these, light calcium carbonate is preferred from the viewpoint of easier adjustment of the amounts of elements in the calcium carbonate.

[0039] In this embodiment, the calcium carbonate powder is preferably a powder made from concrete sludge, steel slag, carbide slag, waste concrete, coal ash, biomass ash, incineration ash such as garbage incineration ash, waste gypsum, alkaline wastewater, or the like, more preferably a calcium carbonate powder made from at least one selected from the group consisting of carbide slag, waste gypsum, coal ash, and incineration ash, even more preferably a calcium carbonate powder made from at least one of carbide slag and waste gypsum, still more preferably a calcium carbonate powder made from waste gypsum, and most preferably a calcium carbonate powder made from waste gypsum. Calcium carbonate powders made from these raw materials allow the amounts of silicon, aluminum, iron, and magnesium to be easily adjusted within the ranges described below.

[0040] In this way, calcium-containing waste, such as steel slag or carbide slag, or calcium extracted from such waste, is reacted with carbon dioxide, which causes the greenhouse effect, to prepare calcium carbonate powder, thereby reducing the environmental load.

[0041] Regarding the lower limit of the above (Requirement 1), when the amount of silicon element in the inorganic powder is 0.05% by mass or more, the resin composition can be imparted with opacifying properties in the visible light region. Similarly, from the viewpoint of easily enhancing the opacifying properties, the amount of silicon element in the inorganic powder is preferably 0.08% by mass or more, more preferably 0.10% by mass or more, and even more preferably 0.20% by mass or more.

[0042] Regarding the upper limit of (Requirement 1), if the amount of silicon element in the inorganic powder is 1.00% by mass or less, the appearance (color) and strength of the obtained molded article are less likely to deteriorate, and wear of parts of the molding machine used to mold the resin composition is more likely to be reduced. From the same viewpoint, the amount of silicon element in the inorganic powder is preferably 0.70% by mass or less, more preferably 0.50% by mass or less, and even more preferably 0.40% by mass or less.

[0043] Regarding the lower limit of the above (Requirement 2), when the amount of aluminum element in the inorganic powder is 0.03% by mass or more, the resin composition can be imparted with opacifying properties in the visible light region. Similarly, from the viewpoint of easily enhancing the opacifying properties, the amount of aluminum element in the inorganic powder is preferably 0.06% by mass or more, and more preferably 0.10% by mass or more.

[0044] Regarding the upper limit of (Requirement 2), if the amount of aluminum element in the inorganic powder is 0.40% by mass or less, the appearance (color) and strength of the obtained molded article are less likely to deteriorate, and wear of parts of the molding machine used to mold the resin composition is more likely to be reduced. From the same viewpoint, the amount of aluminum element in the inorganic powder is preferably 0.35% by mass or less, more preferably 0.30% by mass or less, and even more preferably 0.20% by mass or less.

[0045] Regarding the lower limit of the above (Requirement 3), when the amount of iron element in the inorganic powder is 0.03% by mass or more, the resin composition can be imparted with opacifying properties in the visible light region. Similarly, from the viewpoint of easily enhancing the opacifying properties, the amount of iron element in the inorganic powder is preferably 0.06% by mass or more, more preferably 0.10% by mass or more, and even more preferably 0.20% by mass or more.

[0046] Regarding the upper limit of (Requirement 3), if the amount of iron element in the inorganic powder is 0.40 mass% or less, the strength of the molded product is less likely to decrease due to oxidative degradation of the resin over time. From the same perspective, the amount of iron element in the inorganic powder is preferably 0.35 mass% or less.

[0047] Regarding the lower limit of the above (Requirement 4), when the amount of magnesium element in the inorganic powder is 0.02% by mass or more, the resin composition can be imparted with opacifying properties in the visible light region. Similarly, from the viewpoint of easily enhancing the opacifying properties, the amount of magnesium element in the inorganic powder is preferably 0.05% by mass or more, and more preferably 0.07% by mass or more.

[0048] Regarding the upper limit of (Requirement 4), if the amount of magnesium element in the inorganic powder is 0.50% by mass or less, the appearance (color) and strength of the obtained molded article are less likely to deteriorate, and wear of parts of the molding machine used to mold the resin composition is more likely to be reduced. From the same viewpoint, the amount of silicon element in the inorganic powder is preferably 0.40% by mass or less, more preferably 0.30% by mass or less, and even more preferably 0.20% by mass or less.

[0049] With regard to the above (Requirements 1) to (Requirements 4), the silicon element, aluminum element, iron element, and magnesium element may be contained in the inorganic powder either as a simple substance or as a compound with other elements such as an oxide, sulfide, nitride, sulfide, etc. When two or more types of inorganic powder are contained, the amount of each element in the inorganic powder refers to the mass ratio of the total amount of each element to the total amount of the inorganic powder.

[0050] The types and amounts of elements contained in the inorganic powder are measured by X-ray fluorescence analysis (XRF) using the following procedure. Approximately 30 mg of inorganic powder is placed in an aluminum pan with an inner diameter of 30 mm and a depth of 5 mm, and a pressure of 20 MPa is applied for 2 seconds to produce a molded plate. The obtained molded plate is subjected to X-ray fluorescence analysis using an X-ray fluorescence analyzer (e.g., Rigaku Corporation, ZSX Primus IV) under the following conditions to identify the types and amounts of elements contained in the inorganic powder. (Measurement conditions) X-ray tube: Rh target 4kW X-ray irradiation method: Top irradiation Measuring diameter: 10 mm Integration time: 30 minutes per sample Detected elements: B to U Measurement atmosphere: under vacuum

[0051] The elements in the inorganic powder can be quantitatively determined by the fundamental parameter method.

[0052] Furthermore, when the above measurements are performed on inorganic powder separated and recovered from the resin composition, a method for separating and recovering the inorganic powder from the resin composition can be used, for example, by heating the resin composition at 550°C for 30 minutes to heat and incinerate the organic matter, and then recovering the inorganic powder remaining as residue.

[0053] The amounts of the silicon element, aluminum element, iron element, and magnesium element in the inorganic powder can be adjusted by any method.

[0054] For example, when the inorganic powder is calcium carbonate powder, the amount of each of the elements can be adjusted by using a calcium-containing compound containing silicon, aluminum, iron, and magnesium as a raw material and performing appropriate purification during the calcium carbonate synthesis process.

[0055] in particular, 1) preparing a calcium-containing solution containing calcium extracted from calcium-containing waste, such as carbide slag or waste gypsum; 2) introducing carbon dioxide into the calcium-containing solution while adjusting the pH to partially precipitate calcium carbonate; The following method can be mentioned.

[0056] In this method, the precipitate formed in step 2) contains a large amount of trace elements such as silicon, aluminum, iron, and magnesium. Therefore, by adjusting the ratio of the precipitated elements, the amounts of silicon, aluminum, iron, magnesium, etc. in the resulting calcium carbonate powder can be adjusted.

[0057] On the other hand, when a calcium-containing compound containing small amounts or almost no silicon, aluminum, iron, or magnesium elements is used as a raw material, the content of each element can be adjusted by adding a source of each element during the calcium carbonate synthesis process (carbonation process). The source of each element can be inorganic acid salts (e.g., chlorides, sulfates, carbonates, etc.), organic acid salts, oxides, hydroxides, etc. of silicon, aluminum, iron, and magnesium.

[0058] Furthermore, the amount of each element may be adjusted by mixing the calcium carbonate powder with the source of each element.

[0059] The shape of the inorganic powder is not particularly limited, and may be any of particles, flakes, granules, fibers, etc. In addition, in the case of particles, they may be spherical as obtained by general synthesis methods, or may be irregularly shaped as obtained by pulverizing collected natural minerals.

[0060] Here, the inorganic powder may be surface-modified or may not be surface-modified. From the viewpoint of improving dispersibility, it is preferable that the inorganic powder be surface-modified. Examples of methods for surface modification of inorganic powders include physical modification methods such as plasma treatment and chemical modification methods using coupling agents, surfactants, etc. Examples of coupling agents that can be used in chemical modification methods include silane coupling agents and titanium coupling agents. As surfactants, any of anionic, cationic, nonionic, and amphoteric surfactants can be used, and examples thereof include higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts.

[0061] The average particle size of the inorganic powder is not particularly limited and can be appropriately selected depending on the shape and thickness of the molded article, but is preferably 0.7 μm to 10.0 μm, and more preferably 0.7 μm to 6.0 μm. When the average particle size of the inorganic powder is 10.0 μm or less, the inorganic powder is less likely to fall off from the molded article obtained from the resin composition. When the average particle size of the inorganic powder is 0.7 μm or more, the viscosity when kneaded with the thermoplastic resin is more likely to fall within the desired range.

[0062] The average particle size of the inorganic powder is a value calculated from the results of measuring the specific surface area by an air permeability method in accordance with JIS M 8511: 2014. An example of the measuring instrument is the SS-100 specific surface area measuring device manufactured by Shimadzu Corporation.

[0063] The content of inorganic powder in the resin composition is not particularly limited, but is preferably 15% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 75% by mass or less, and even more preferably 30% by mass or more and 65% by mass or less, relative to the total amount of the resin composition. When the content of inorganic powder is equal to or greater than the lower limit, the mechanical strength of the resin composition can be further increased. When the content of inorganic powder is equal to or less than the upper limit, the moldability and appearance can be further maintained. The content of calcium carbonate powder in the inorganic powder may be, for example, 50% by mass or more, 70% by mass or more, or 100% by mass.

[0064] 1-3.Other ingredients The resin composition may further contain other components in addition to those described above, provided that the purpose and effect of the present embodiment are not impaired. Examples of the other components include lubricants, plasticizers, colorants, antioxidants, flame retardants, foaming agents, and flow control agents.

[0065] Examples of lubricants include fatty acid-based lubricants such as stearic acid, hydroxystearic acid, complex stearic acid, and oleic acid; fatty alcohol-based lubricants; aliphatic amide-based lubricants such as stearamide, oxystearamide, oleylamide, erucylamide, ricinoleamide, behenamide, methylolamide, methylenebisstearamide, methylenebisstearobenamide, bisamic acids of higher fatty acids, and complex amides; aliphatic ester-based lubricants such as n-butyl stearate, methyl hydroxystearate, polyhydric alcohol fatty acid esters, saturated fatty acid esters, and ester waxes; and fatty acid metal soap-based lubricants such as zinc stearate and magnesium stearate.

[0066] Examples of plasticizers include triethyl citrate, acetyl triethyl citrate, dibutyl phthalate, diaryl phthalate, dimethyl phthalate, diethyl phthalate, dioctyl phthalate, di(2-ethylhexyl) phthalate, di-2-methoxyethyl phthalate, dibutyl tartrate, o-benzoylbenzoic acid ester, diacetin, epoxidized soybean oil, etc. The resin composition may contain these alone or in combination.

[0067] The coloring material may be any of known organic or inorganic pigments or dyes. Specific examples of coloring materials include organic pigments such as azo-based, anthraquinone-based, phthalocyanine-based, quinacridone-based, isoindolinone-based, dioxazine-based, perinone-based, quinophthalone-based, and perylene-based pigments; and inorganic pigments such as ultramarine, titanium yellow, and chromium oxide. The resin composition may contain these pigments alone or in combination.

[0068] Examples of antioxidants include phosphorus-based antioxidants, phenol-based antioxidants, and pentaerythritol-based antioxidants. The resin composition may contain these antioxidants alone or in combination. Phosphorus-based antioxidants, more specifically, phosphorus-based antioxidants such as phosphites and phosphate esters, are preferably used. Examples of phosphites include triesters, diesters, and monoesters of phosphorous acid, such as triphenyl phosphite, trisnonylphenyl phosphite, and tris(2,4-di-t-butylphenyl) phosphite.

[0069] Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris(nonylphenyl) phosphate, 2-ethylphenyldiphenyl phosphate, and the like.

[0070] Examples of phenolic antioxidants include α-tocopherol, butylhydroxytoluene, sinapyl alcohol, vitamin E, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-t-butyl-6-(3'-t-butyl-5'-methyl-2'-hydroxybenzyl)-4-methylphenylacrylate, 2,6-di-t-butyl-4-(N,N-dimethylaminomethyl)phenol, 3,5-di-t-butyl-4-hydroxybenzylphosphonate diethyl ester, and tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane.

[0071] The flame retardant is not particularly limited, but may be, for example, a halogen-based flame retardant or a non-phosphorus-based halogen-based flame retardant such as a phosphorus-based flame retardant or a metal hydrate. The resin composition may contain one or more of these.

[0072] Examples of halogen-based flame retardants include halogenated bisphenol compounds such as halogenated bisphenylalkanes, halogenated bisphenylethers, halogenated bisphenylthioethers, and halogenated bisphenylsulfones, as well as bisphenol-bis(alkyl ether) compounds such as brominated bisphenol A, brominated bisphenol S, chlorinated bisphenol A, and chlorinated bisphenol S. Examples of phosphorus-based flame retardants include aluminum tris(diethylphosphinate), bisphenol A bis(diphenylphosphate), triarylisopropyl phosphate, cresyl di-2,6-xylenyl phosphate, and aromatic condensed phosphate esters. Examples of metal hydrates include aluminum trihydrate, magnesium dihydroxide, and combinations thereof.

[0073] The flame retardant may also be combined with a flame retardant synergist. Examples of the flame retardant synergist include antimony oxides such as antimony trioxide and antimony pentoxide, and other known flame retardant synergists.

[0074] The foaming agent is not particularly limited as long as it is a compound that can generate bubbles when mixed or injected into a composition that is in a molten state in a melt kneader. Examples of foaming agents include those that generate bubbles by changing phase from solid to gas, those that generate bubbles by changing phase from liquid to gas, those that generate gas by decomposition of a solid or liquid, and gas itself.

[0075] Examples of blowing agents include aliphatic hydrocarbons such as propane, butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclobutane, cyclopentane, and cyclohexane; halogenated hydrocarbons such as chlorodifluoromethane, difluoromethane, trifluoromethane, trichlorofluoromethane, dichloromethane, dichlorofluoromethane, dichlorodifluoromethane, chloromethane, chloroethane, dichlorotrifluoroethane, dichloropentafluoroethane, tetrafluoroethane, difluoroethane, pentafluoroethane, trifluoroethane, dichlorotetrafluoroethane, trichlorotrifluoroethane, tetrachlorodifluoroethane, and perfluorocyclobutane; thermally decomposable compounds such as azodicarbonamide, N,N'-dinitropentamethylenetetramine, 4,4'-oxybisbenzenesulfonylhydrazide, carbon dioxide, and sodium hydrocarbon; inorganic gases such as nitrogen and air; and water.

[0076] The foaming agent may contain an active ingredient of the foaming agent together with a carrier resin. Examples of the carrier resin include crystalline olefin resins such as crystalline propylene. Examples of the active ingredient include bicarbonates. Among these, bicarbonates are preferred. A foaming agent concentrate containing a crystalline polypropylene resin as the carrier resin and bicarbonates as the thermal decomposition type foaming agent is preferred.

[0077] Known fluidity modifiers can also be used. Examples of fluidity modifiers include peroxides such as dialkyl peroxides, for example, 1,4-bis[(t-butylperoxy)isopropyl]benzene. Depending on the type of thermoplastic resin used, these peroxides can also function as crosslinking agents. In particular, when the thermoplastic resin (polyolefin resin) has a diene-derived structural unit, the diene may be crosslinked by the peroxide.

[0078] Examples of antistatic agents include fatty acid diethanolamides such as lauryl diethanolamide and stearyl diethanolamide; and hydroxyl group-containing compounds such as alcohol amine compounds. Alcohol amines, such as monoethanolamine, diethanolamine, and triethanolamine, are particularly preferred. Two or more types of antistatic agents can also be used in combination. These antistatic agents may be supported on calcium silicate, calcium carbonate, or the like. The number of carbon atoms in the acyl group of the fatty acid diethanolamide is preferably 8 to 22, in order to achieve sufficient antistatic effect.

[0079] The total amount of other components in the resin composition is not particularly limited, but can be, for example, 5% by mass or less relative to the total amount of the resin composition.

[0080] 1-4. Shape of resin composition The shape of the resin composition according to this embodiment is not particularly limited, and may be any shape, such as particulate, pellet, or block. When the resin composition is in pellet form, the shape of the pellet is not particularly limited, and may be any shape, such as cylindrical, spherical, or oval sphere. The size is also not particularly limited, and is selected appropriately depending on the shape. For example, in the case of spherical pellets, the diameter may be 1 to 10 mm. In the case of oval sphere pellets, the major axis may be about 1 to 10 mm, and the aspect ratio may be about 0.1 to 1.0. In the case of cylindrical pellets, the diameter may be about 1 to 10 mm, and the height may be about 1 to 10 mm.

[0081] 1-5.Method for producing resin composition The resin composition according to this embodiment can be produced through a process of mixing the above-described thermoplastic resin, inorganic powder, and, if necessary, other components.

[0082] The mixing method is not particularly limited, and may be, for example, a method by melt kneading. All components may be mixed and then melt kneaded, or only some of the components may be melt kneaded first and the remaining components may be kneaded later. The device for melt kneading is not particularly limited, and a general extruder, kneader, Banbury mixer, etc. can be used. From the viewpoint of obtaining a resin composition with a particularly uniform composition, kneading with a twin-screw kneader is preferred.

[0083] 2. Molded products The molded article according to this embodiment is molded using the above resin composition by a known method.

[0084] The shape and use of the molded product are not particularly limited, and it can be used for films, sheets, containers (food containers, etc.), daily necessities, automobile parts, electric and electronic parts, various consumables, etc. For example, the above-mentioned resin composition can be extruded into an extrusion-molded sheet.

[0085] The molded article preferably has voids inside, which causes a difference in refractive index at the interface between the resin composition and air, thereby increasing light scattering and facilitating an increase in whiteness.

[0086] Among the above-mentioned molded products having voids, the measured density ρ m and the theoretical density ρ of the molded product t And, ρ m ≦0.80ρ t It is preferable that the relationship of 0.50ρ t ≦ρ m ≦0.70ρ t It is more preferable that the relationship ρ m is 0.80ρ t If the thickness is less than this, many voids are present, which increases the area of ​​the interface between the resin composition and air, thereby increasing the light scattering property and facilitating an increase in whiteness. m is 0.50ρ t If the thickness is more than this, breakage or the like is unlikely to occur during handling, and handling properties are good.

[0087] In the formula, the theoretical density ρ t indicates the density when the molded body has no voids, and is a value calculated by the following method: the molded body is heated to a temperature at least 50°C higher than the melting point (for example, 230°C when polyethylene or polypropylene is used as the thermoplastic resin) for 30 minutes to melt it, and then thoroughly degassed, and measured using a hydrometer.

[0088] Also, the measured density ρ m is a value measured using an electronic hydrometer by the liquid weighing method in accordance with JIS Z 8807:2012, using ethanol as the solvent.

[0089] Regarding the transmittance of the molded article in the visible light region, the average transmittance of light from 350 nm to 700 nm is preferably less than 5.0%. A transmittance of less than 5.0% ensures sufficient light shielding. From the same perspective, it is more preferably less than 2.0%, and even more preferably less than 1.0%. The average transmittance of light from 350 nm to 700 nm is calculated by arithmetically averaging the transmittance of light from 350 nm to 700 nm measured using a UV-3600i Plus ultraviolet-visible-infrared spectrophotometer (Shimadzu Corporation) at a measurement wavelength of 210 nm to 800 nm, a scan speed of 600 nm / min, and a measurement wavelength interval of 1 nm.

[0090] From the viewpoint of enhancing designability, the whiteness of the molded article is preferably 40 or more, and more preferably 80 or more. The whiteness is measured using an ultraviolet-visible-infrared spectrophotometer UV-3600i Plus (manufactured by Shimadzu Corporation) with a light source C and a viewing angle of 2° to obtain tristimulus values ​​according to a method in accordance with JIS Z 8722:2009 from the reflectance results, and then the CIE whiteness is calculated from the obtained tristimulus values ​​according to a method in accordance with JIS Z 8715:1999.

[0091] Generally, when a material is made into a thin film, the light-shielding property and scattering property are reduced, and the hiding property and scattering property are difficult to exhibit. On the other hand, the molded article according to the present embodiment has excellent hiding property and scattering property, and therefore exhibits the hiding property and scattering property even when made into a thin film molded article such as a film, a sheet, etc., and can therefore be suitably used as a thin film molded article.

[0092] When a thin film is molded, the thickness of the molded product is preferably 40 μm to 450 μm, and more preferably 80 μm to 350 μm. If the thickness is 40 μm or more, sufficient light shielding properties in the visible light region can be exhibited. If the thickness is 450 μm or less, the molded product can be made lighter, allowing for a reduction in the amount of material used.

[0093] 3. Manufacturing method of molded products The molded article according to this embodiment is molded using the above resin composition by a known method.

[0094] The molding method is not particularly limited, and may be any of inflation molding, extrusion molding, injection molding, foam injection molding, injection compression molding, blow molding, press molding, calendar molding, vacuum molding, and the like.

[0095] The method for producing the voided molded article is not particularly limited, but for example, a known foaming agent may be melt-kneaded, or a film-shaped molded article may be formed and then stretched. Among these, from the viewpoint of easily improving light scattering, it is preferable to form voids by stretching. This is thought to be because inorganic powders are usually more difficult to stretch by stretching than thermoplastic resins, so the inorganic powder cannot fully follow the stretching caused by the thermoplastic resin, and voids are more likely to be formed near the inorganic powder, which has a relatively high refractive index, making it easier to improve light scattering.

[0096] The method for stretching the film-like formed body is not particularly limited, and any known stretching method can be used, including roll stretching, tenter stretching, simultaneous biaxial stretching, and rolling.

[0097] The stretching process may be uniaxial stretching or biaxial stretching. The biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching in which longitudinal (lengthwise) stretching and transverse (widthwise) stretching are performed sequentially. In sequential biaxial stretching, the longitudinal and transverse stretching may be performed in this order, or transverse stretching may be performed first.

[0098] The stretching ratio is preferably 1.1 to 5.0 times, and more preferably 1.5 to 5.0 times. When the stretching ratio is 1.1 times or more, voids are easily formed in the molded product to an appropriate degree, which tends to improve light scattering. When the stretching ratio is 5.0 times or less, the size of the voids can be appropriately controlled, which makes it less likely that problems such as breakage will occur during stretching, and also makes it less likely that distortion will occur in the areas where voids are formed. When biaxial stretching (longitudinal stretching and transverse stretching) is performed, the stretching ratio refers to the product of the stretching ratio in the longitudinal direction and the stretching ratio in the transverse direction.

[0099] The stretching temperature is not particularly limited, but is preferably a temperature below the melting point of the thermoplastic resin, more preferably 15°C below the melting point, and even more preferably 30°C below the melting point. The lower limit of the stretching temperature is not particularly limited, but can be a temperature 100°C below the melting point or higher. By setting the stretching temperature to a temperature 100°C below the melting point or higher, the size of voids can be appropriately controlled, making it less likely that problems such as breakage will occur during stretching. Furthermore, by setting the temperature below the melting point, voids are more likely to occur during stretching, making it easier to improve hiding power and scattering properties. The melting point of the thermoplastic resin is a value measured by DSC or the like.

[0100] Furthermore, if necessary, from the viewpoint of improving thermal shrinkage and dimensional stability, the stretched film may be subjected to heat treatment near the melting point or relaxation. The heat treatment can be carried out by any known method, such as contact heating with a heated roll or heating in air in an oven. It is also possible to repurpose the above-mentioned stretching device. The heat treatment temperature can be any temperature below the melting point of the resin composition, but is preferably 100°C or higher and below the melting point of the resin composition. [Example]

[0101] The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

[0102] 1. Material Preparation The following materials were used to prepare the resin compositions of the examples and comparative examples.

[0103] 1-1.Inorganic powder Inorganic powder: calcium carbonate powder shown in Table 1 below In Table 1, CC-2 to CC-5 are calcium carbonate powders prepared from the calcium-containing raw materials shown in Table 1, and CC-6 to CC-10 are calcium carbonate powders obtained by mixing these. CC-11 to CC-13 are calcium carbonate powders obtained in the same manner as CC-5, except that calcium silicate, aluminum oxide, and iron oxide were added to the calcium-containing solution obtained from waste gypsum so as to achieve the element concentrations shown in Table 1.

[0104] [Table 1]

[0105] In the table, "ND" indicates that the concentration was below the detection limit, ie, less than 0.01% by mass.

[0106] (Method for determining elements in calcium carbonate powder) The amount of each element contained in the calcium carbonate powder was measured by the following method. Approximately 30 mg of calcium carbonate powder was placed on an aluminum pan with an inner diameter of 30 mm and a depth of 5 mm, and pressed at 20 MPa for 2 seconds to produce a molded plate. The obtained molded plate was subjected to fluorescent X-ray analysis under the following conditions to measure the amount of elements contained in the calcium carbonate powder. (Measurement conditions) Equipment: X-ray fluorescence analyzer ZSX Primus IV (Rigaku Corporation) X-ray tube: Rh target 4kW X-ray irradiation method: Top irradiation Measuring diameter: 10 mm Integration time: 30 minutes per sample Detected elements: B to U Measurement atmosphere: under vacuum

[0107] The quantitative determination of each element in the calcium carbonate powder was carried out by the fundamental parameter method.

[0108] 1-2.Thermoplastic resin PP (homopolypropylene, Prime Polymer E111G) PE (high density polyethylene, HF313 manufactured by Japan Polyethylene Corporation)

[0109] 1-3.Other Lubricant (stearic acid, manufactured by Kao Corporation) Antistatic agent (lithium salt, manufactured by Marubishi Yuka Kogyo Co., Ltd.) Antioxidant 1 (phenolic antioxidant, manufactured by ADEKA) Antioxidant 2 (phosphite antioxidant, manufactured by ADEKA)

[0110] 2. Preparation of resin compositions and molded products [Examples 1 to 5, Comparative Examples 1 to 13] (Pellet production) The thermoplastic resin, inorganic powder, and other components were fed into a Parker HK-25D co-rotating twin-screw kneading extruder (φ25 mm, L / D=41) in the mass ratios shown in Tables 2 and 3, melt-kneaded at a cylinder temperature of 230°C, and then extruded into strands. The extruded resin composition was then cooled and cut to obtain pellets of the resin composition.

[0111] (Sheet production) The obtained pellets were charged into a T-die extrusion molding device (φ20 mm, L / D=25) manufactured by Toyo Seiki Seisaku-sho, and extruded at 240° C. to obtain a sheet having a thickness of 400 μm.

[0112] [Example 6, Comparative Example 14] As shown in Table 3, pellets of the resin composition were obtained in the same manner as in Example 1, except that the thermoplastic resin was changed to PE and the cylinder temperature was changed to 220°C, and then a sheet was produced.

[0113] [Example 7, Comparative Example 15] In Example 7 and Comparative Example 14, sheets having a thickness of 300 μm were prepared in the same manner as in Example 1 and Comparative Example 1, except that when extruding from the extrusion molding device, the casting temperature was 70°C, the stretching temperature was 100°C, and the sheet was stretched 2.0 times in the take-up direction.

[0114] [Theoretical density ρ t , measured density ρ m Measurement of Theoretical density ρ of each molded product t , measured density ρ m The theoretical density of each molded product was as shown in Tables 2 and 3. t The density ρ of each molded product was measured using a hydrometer after it was heated at 230°C for 30 minutes to melt it and then thoroughly degassed. m is a value measured using an electronic hydrometer by the liquid weighing method in accordance with JIS Z 8807:2012, using ethanol as the solvent.

[0115] 3. Evaluation The sheets obtained in Examples 1 to 7 and Comparative Examples 1 to 15 were evaluated as follows.

[0116] 3-1. Hiding ability in the visible light range The prepared sheet was cut into a size of 50 mm x 50 mm to prepare a test piece. The spectral light transmittance of this test piece was measured using an ultraviolet-visible-infrared spectrophotometer. The measurement conditions were as follows. Then, the opacity in the visible light region was evaluated based on the average transmittance of light from 350 nm to 700 nm, according to the following criteria. A grade of C or higher was considered to be acceptable. (Measurement conditions) Equipment: UV-3600i Plus ultraviolet-visible infrared spectrophotometer (Shimadzu Corporation) Measurement wavelength range: 210 to 800 nm Scan speed: 600nm / min Measurement wavelength interval: 1nm

[0117] (Judgment criteria) A: The average transmittance of light from 350nm to 700nm is less than 1.0% B: The average transmittance of light from 350 nm to 700 nm is 1.0% or more and less than 2.0% C: The average transmittance of light from 350 nm to 700 nm is 2.0% or more and less than 5.0% D: Average transmittance of light from 350nm to 700nm is 5.0% or more

[0118] 3-2.Whiteness The whiteness of the test piece used in the above transmittance measurement was the CIE whiteness calculated using tristimulus values ​​obtained from the reflectance measured using an ultraviolet-visible-infrared spectrophotometer. The measurement conditions were as follows. Note that all of the ratings A to C were at a level that would not pose a problem in practical use. Equipment: UV-3600i Plus ultraviolet-visible infrared spectrophotometer (Shimadzu Corporation) Light source: C light source Viewing angle: 2° Calculation of tristimulus values: Method conforming to JIS Z 8722:2009 Calculation of CIE whiteness: Method based on JIS Z 8715:1999

[0119] (Judgment criteria) A: Whiteness of 80 or more B: Whiteness is 40 or more and less than 80 C: Whiteness less than 40

[0120] 3-3.Durability Dumbbell-shaped test pieces were prepared from the test pieces used in the transmittance measurements in accordance with JIS K7161-2:2014. In accordance with JIS K 7212:1999, tensile tests were performed on the dumbbell test pieces after storing them in an environment at 100°C for 500 hours, and the results were evaluated based on the following criteria. A grade of B or higher was considered acceptable.

[0121] (Judgment criteria) A: Tensile elongation is 150% or more B: Tensile elongation is 100% or more and less than 150% C: Tensile elongation is less than 100%

[0122] 3-3. Wear of molding machines After the moldings were produced, the screws were removed from the small twin-screw extruder, washed and dried, and the presence and extent of wear marks on the surface were visually evaluated according to the following criteria.

[0123] (Judgment criteria) A: No wear marks were observed on the screw surface. B: Slight wear marks were observed on the screw surface. C: Wear marks were clearly observed on the screw surface.

[0124] 3-4.Evaluation results The evaluation results of Examples 1 to 7 and Comparative Examples 1 to 15 are shown in Tables 2 and 3.

[0125] The optical spectra in the visible light region of the molded bodies of Examples 2 and 7 and Comparative Example 1 are shown in FIG.

[0126] [Table 2]

[0127] [Table 3]

[0128] As shown in Tables 2 and 3, when the inorganic powder satisfies the above requirements 1 to 4 (comparison between Examples and Comparative Examples), it is found that the resin composition has excellent durability, can suppress wear on the molding machine, and has good hiding power in the visible light region.

[0129] Among these, it is clear that when the thermoplastic resin and inorganic powder are contained in a mass ratio of 25:75 to 75:25, the hiding power in the visible light region becomes better (comparison of Examples 2, 4, and 5).

[0130] Also, ρ m ≦0.80ρ t This makes it possible to easily increase the light scattering property, and it is understood that the hiding power and whiteness in visible light become better (comparison between Examples 2 and 7).

[0131] Furthermore, it can be seen that when the content of each element of the above requirements 1 to 4 is within or above the more preferred range (the amount of silicon element in the inorganic powder is 0.10 mass% or more, the amount of aluminum element is 0.10 mass% or more, the amount of iron element is 0.10 mass% or more, and the amount of magnesium element is 0.07 mass% or more), the light-blocking properties for visible light are further improved (comparison with Examples 1 to 3). [Industrial Applicability]

[0132] According to the present invention, it is possible to provide a resin composition that is excellent in durability, can suppress wear on a molding machine, and has good hiding power in the visible light region, and a molded article containing the same.

Claims

1. The thermoplastic resin and the inorganic powder are contained in a mass ratio of 10:90 to 80:20, The amount of silicon element in the inorganic powder is 0.05% by mass or more and 1.00% by mass or less, The amount of aluminum element in the inorganic powder is 0.03% by mass or more and 0.40% by mass or less, The amount of iron element in the inorganic powder is 0.03% by mass or more and 0.40% by mass or less, The amount of magnesium element in the inorganic powder is 0.02% by mass or more and 0.50% by mass or less. Resin composition.

2. The amount of silicon element in the inorganic powder is 0.08% by mass or more and 0.70% by mass or less, The amount of aluminum element in the inorganic powder is 0.06% by mass or more and 0.35% by mass or less, the amount of iron element in the inorganic powder is 0.06% by mass or more and 0.35% by mass or less, The amount of magnesium element in the inorganic powder is 0.05% by mass or more and 0.40% by mass or less. The resin composition according to claim 1.

3. The thermoplastic resin includes a polypropylene-based resin and / or a polyethylene-based resin. The resin composition according to claim 1.

4. The inorganic powder is calcium carbonate powder. The resin composition according to claim 1.

5. The calcium carbonate powder includes calcium carbonate powder made from at least one material selected from the group consisting of carbide slag, waste gypsum, coal ash, and incineration ash. The resin composition according to claim 4.

6. The calcium carbonate powder has an average particle size of 0.7 μm or more and 10.0 μm or less, as measured by an air permeability method in accordance with JIS M 8511:2014. The resin composition according to claim 5.

7. The thermoplastic resin and the inorganic powder are contained in a mass ratio of 25:75 to 75:

25. The resin composition according to claim 1.

8. A molded article comprising the resin composition according to any one of claims 1 to 7.

9. The molded article according to claim 8 , wherein the resin composition constituting the molded article has voids inside.

10. The measured density ρ of the molded product ｍ and the theoretical density ρ of the molded product t and satisfy the relationship of the following formula (I): The molded article according to claim 9. Formula (I) ρ ｍ ≦ 0.80ρ t (In the formula, the theoretical density ρ t indicates the density when the molded product has no voids.)

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