Polypropylene resin composition

Abstract

To provide a polypropylene resin composition containing a biomass material, yet being improved in the odor and in the formability.SOLUTION: The polypropylene resin composition is composed of a polypropylene resin (A) of 35 mass% to 69 mass%, a compatibilizer (B) of 1 mass% to 5 mass%, a biomass filler (C) of Mc mass%, and an inorganic filler (D) of Md mass%, wherein the total (Mc+Md) of the biomass filler (C) and the inorganic filler (D) is 30 to 60 mass%, and the relationship Mc≥Md>0 is satisfied.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polypropylene resin composition containing a biomass material and an inorganic filler, and to an extrusion-molded article, an injection-molded article, a thermoformed article, or a blow-molded article made from the polypropylene resin composition. [Background technology]

[0002] Polypropylene has excellent properties, such as being lightweight, relatively strong, highly heat-resistant, and easily moldable, and is therefore used worldwide in a wide range of product fields, including everyday items and automotive components. In recent years, there has been a demand to reduce the amount of plastic used as a measure to address environmental issues. As part of this effort, many proposals have been made to combine biomass materials, such as wood flour, which are inedible and non-exhaustible resources and can adsorb and fix CO2 from the atmosphere, with polypropylene (e.g., Patent Document 1).

[0003] When polypropylene resin compositions made by compounding polypropylene and biomass materials are molded into various molded products, the processing temperature reaches 180 to 200°C. At these temperatures, the biomass materials undergo thermal decomposition, producing a burnt odor. Increasing the biomass material loading rate to reduce the amount of plastic used further worsens the odor. Furthermore, highly loaded polypropylene with biomass materials reduces fluidity, resulting in poor moldability, especially in extrusion molding and thermoforming.

[0004] For this reason, its current applications are limited to products such as thick wood decking materials where the surface condition can be adjusted through post-processing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-80832 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to provide a polypropylene resin composition that solves the above problems and has improved odor and moldability while blending a relatively large amount of biomass material into polypropylene. [Means for solving the problem]

[0007] The polypropylene resin composition of the present invention is characterized in that it comprises 35% by mass to 69% by mass of polypropylene resin (A), 1% by mass to 5% by mass of compatibilizer (B), Mc% by mass of biomass filler (C), and Md% by mass of inorganic filler, the total (Mc+Md) of the biomass filler (C) and the inorganic filler (D) being 30% to 60% by mass, and satisfying Mc≧Md>0.

[0008] The polypropylene resin composition of the present invention comprises a polypropylene resin (A) 43 % by mass to 69% by mass, compatibilizer (B) 1% by mass~ 3 % by mass, biomass filler (C) is Mc% by mass, and inorganic filler (D) is Md% by mass, and the total of biomass filler (C) and inorganic filler (D) (Mc + Md) is 30 to 55 Mass % and Mc≧Md>0 and further containing 1 to 50 parts by mass of a thermoplastic elastomer (E) for 100 parts by mass of the polypropylene resin (A), the compatibilizer (B), the biomass filler (C), and the inorganic filler (D), which are 100% by mass in total. It is characterized by:

[0009] The biomass filler (C) is preferably at least one plant-derived filler selected from the group consisting of wood, pulp, bamboo, sugarcane (bagasse), rice husks, and rice (starch).

[0010] The inorganic filler (D) is preferably at least one selected from the group consisting of talc, calcium carbonate, shirasu balloon, perlite, aluminum hydroxide, and mica.

[0011] The average particle size of the biomass filler (C) is preferably 5 to 300 μm.

[0012] The specific surface area (BET method) of inorganic filler (D) is 5m 2 / g or more.

[0013] It is preferable that the composition further contains 10 to 50 parts by mass of a thermoplastic elastomer (E) for 100 parts by mass of the polypropylene resin (A), the compatibilizer (B), the biomass filler (C), and the inorganic filler (D), which together make up 100% by mass. The thermoplastic elastomer (E) preferably has a melt flow rate (MFR) of 0.1 to 10 g / 10 min, measured at 190° C. under a load of 2.16 kg.

[0014] Furthermore, the extrusion molded product, injection molded product, thermoformed product, or blow molded product is preferably made of the above-mentioned polypropylene resin composition. [Effects of the Invention]

[0015] The polypropylene resin composition of the present invention can improve moldability, odor, and physical properties while maintaining a high bio-content. DETAILED DESCRIPTION OF THE INVENTION

[0016] Polypropylene resin (A) The polypropylene resin (A) is preferably one or more polypropylene resins selected from the group consisting of propylene homopolymer, propylene-ethylene block copolymer, propylene-ethylene-1-butene block copolymer, propylene-ethylene random copolymer, propylene-1-butene random copolymer, propylene-ethylene-1-butene random copolymer, propylene-ethylene random block copolymer, and propylene-ethylene-1-butene random block copolymer.

[0017] Examples of polypropylene resin (A) include those polymerized with a Ziegler-Natta catalyst, those polymerized with a metallocene catalyst, and those polymerized with a post-metallocene catalyst. Examples of Ziegler-Natta catalysts include catalysts containing a solid component essentially containing titanium, magnesium, and a halogen, an organoaluminum, and an optional electron donor. Examples of metallocene catalysts include catalysts containing a transition metal compound of Group 4 of the periodic table containing a ligand having a cyclopentadienyl skeleton, a co-catalyst, and an optional organometallic compound and support. Examples of post-metallocene catalysts include catalysts containing an organometallic compound such as a bisamide compound of a metal in Group 4 of the periodic table, a bisimino compound of a metal in Groups 8 to 10 of the periodic table, or a salicylaldiminato compound of a metal in Groups 4 to 10 of the periodic table, a co-catalyst, and an optional organometallic compound and support. Commercially available polypropylene resins (A) can be used, such as the Novatec PP series manufactured by Japan Polypropylene Corporation.

[0018] Polypropylene resin (A) is a propylene homopolymer obtained by homopolymerizing propylene in a single stage or two or more multistage polymerizations, a propylene-α-olefin random copolymer obtained by copolymerizing propylene and an α-olefin in a single stage or two or more multistage polymerizations, a polymerization step (1) in which propylene is homopolymerized in a single stage or two or more multistage polymerizations to obtain a propylene homopolymer, and a copolymerization step (2-1) in which propylene and an α-olefin are copolymerized in a single stage or two or more multistage polymerizations to obtain a propylene-α-olefin random copolymer, or a copolymer obtained by copolymerizing two or more α-olefins in a single stage or two or more multistage polymerizations to obtain an α-olefin random copolymer. Examples of the propylene-α-olefin random block copolymer include a copolymerization step (1) in which propylene and an α-olefin are copolymerized in a single stage or two or more stages to obtain a propylene-α-olefin random copolymer, and a copolymerization step (2-1) in which propylene and an α-olefin are copolymerized in a single stage or two or more stages to obtain a propylene-α-olefin random copolymer, or a copolymerization step (2-2) in which two or more α-olefins are copolymerized in a single stage or two or more stages to obtain an α-olefin random copolymer. The polypropylene resin (A) may be a single type or a combination of two or more types.

[0019] The α-olefin is preferably ethylene or an α-olefin having 4 to 18 carbon atoms. Specific examples include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1, 4,4-dimethylpentene-1, etc. The α-olefin may be one type or a combination of two or more types.

[0020] The polypropylene resin (A) preferably has a melt flow rate (MFR) measured at 230°C under a load of 2.16 kg of 0.1 to 150 g / 10 min, more preferably 1 to 100 g / 10 min, and even more preferably 3 to 50 g / 10 min. An MFR within the above range reduces the load on the extruder when extruding a sheet, improving moldability, which is preferable. Here, the MFR is a value measured at 230°C under a load of 2.16 kg in accordance with JIS K7210. The MFR of the polypropylene resin (A) can be adjusted by controlling the hydrogen concentration during polymerization, etc.

[0021] Furthermore, it is preferable to blend in the polypropylene resin (A) so-called high melt tension polypropylene, such as polypropylene crosslinked with electron beams, crosslinked with peroxides, or polypropylene with long chain branches introduced by polymerization, or polypropylene with a wide molecular weight distribution. These high melt tension polypropylenes suppress sagging of the sheet during sheet extrusion, and further suppress sagging of the sheet during secondary molding, and contribute to uniform elongation during stretching, so that they have good processability. It is preferable that the high melt tension polypropylene has a melt tension (MT) represented by the following formula. Melt tension (MT, unit: cN) is Preferably, log(MT)>-0.9×log(MFR)+0.5; and log(MT)<1.40 (MT<25), More preferably, log(MT)>-0.9×log(MFR)+0.6; and log(MT)<1.04 (MT<11), More preferably, log(MT)>-0.9×log(MFR)+0.7, and log(MT)<0.85 (MT<7). Examples of such materials include WAYMAX from Japan Polypropylene Corporation and Daploy from Borealis.

[0022] Here, melt tension (MT) is a value measured using a capillograph. The resin is placed in a 9.6 mm diameter cylinder heated to 230°C and melted, and the molten resin is extruded from an orifice 2.0 mm in diameter and 40 mm long at a pushing speed of 20 mm / min. The extruded resin is taken up at a speed of 4.0 m / min, and the tension (unit: cN) detected on the pulley is measured, and this is taken as the melt tension (MT).

[0023] Compatibilizer (B) The polypropylene resin composition contains a compatibilizer (B). Examples of suitable compatibilizers include saturated carboxylic acids, unsaturated carboxylic acids, or derivatives thereof, thermoplastic resins modified with unsaturated carboxylic acids or derivatives thereof, and cellulosic, lignocellulose, and starch-based materials modified with unsaturated carboxylic acids or derivatives thereof. Furthermore, oil-modified alkyd resins or derivatives thereof, and modified starches or derivatives thereof can also be used.

[0024] Examples of saturated carboxylic acids include succinic anhydride, succinic acid, phthalic anhydride, phthalic acid, tetrahydrophthalic anhydride, adipic acid anhydride, etc. Examples of unsaturated carboxylic acids include maleic anhydride, maleic acid, nadic anhydride, itaconic anhydride, itaconic acid, citraconic anhydride, citraconic acid, crotonic acid, isocrotonic acid, mesaconic acid, angelic acid, sorbic acid, acrylic acid, etc. Examples of derivatives of saturated or unsaturated carboxylic acids that can be used include metal salts, amides, imides, esters, etc. of saturated or unsaturated carboxylic acids.

[0025] Furthermore, the compatibilizer (B) can be a thermoplastic resin modified with an unsaturated carboxylic acid or its derivative, or a cellulosic material, lignocellulose material, or starch material modified with an unsaturated carboxylic acid or its derivative. The thermoplastic resin before modification used in the thermoplastic resin modified with an unsaturated carboxylic acid or its derivative is not particularly limited as long as it does not significantly impair the effects of the present invention. Specific examples include low-density polyethylene, ethylene-α-olefin copolymer, high-density polyethylene, polypropylene, propylene block copolymer, and propylene random copolymer. Of these, it is preferable that the thermoplastic resin is the same as the polypropylene resin (A).

[0026] The compatibilizer (B) can be obtained by heating and mixing a base material such as a thermoplastic resin, a cellulosic material, a lignocellulosic material, or a starch-based material with an unsaturated carboxylic acid or its derivative, and a radical generator in the presence or absence of a solvent. The amount of unsaturated carboxylic acid or its derivative added is preferably 0.1 to 15% by mass, and particularly preferably 1 to 10% by mass. The compatibilizer (B) used in the present invention is preferably a thermoplastic resin modified with an odorless, low-acid unsaturated carboxylic acid or its derivative, or a cellulosic material, lignocellulosic material, or starch-based material modified with an unsaturated carboxylic acid or its derivative.

[0027] The content of the compatibilizer (B) in the polypropylene resin composition is 1 to 5% by mass. If it is less than 1% by mass, the effect of the compatibilizer is not exhibited, and if it exceeds 5% by mass, the impact resistance of the polypropylene resin composition decreases. The content of the compatibilizer (B) in the polypropylene resin composition is preferably 1.5 to 4.5% by mass, more preferably 2 to 4% by mass.

[0028] Biomass filler (C) The biomass filler (C) is an organic resource derived from animals and plants, excluding fossil resources, and is preferably an organic resource derived from plants, excluding fossil resources. Examples of the organic resource derived from plants, excluding fossil resources, include lignocellulose-based materials, cellulose-based materials, and starch-based materials.

[0029] Lignocellulosic materials include lignocellulosic fibers and lignocellulosic powders. Specific examples include wood pulp, refiner graft pulp (RGP), paper pulp, waste paper, crushed wood chips, wood flour, and fruit shell powder. Specific examples of wood flour include crushed pine, fir, poplar, bamboo, bagasse, and oil palm trunks, as well as sawdust and sawdust. Specific examples of fruit shell powder include crushed walnut, peanut, and palm fruit.

[0030] Examples of cellulosic materials include alpha fiber flock obtained by alkali-treating wood pulp and mechanically shredding it, cotton linters obtained from cottonseed, cotton flock, rayon flock obtained by shredding rayon, and cellulose fiber.

[0031] There are no particular limitations on the form of these lignocellulose-based materials and cellulosic materials, and fibrous or powdery materials can be used.

[0032] The lignocellulosic material or cellulose material may be an esterified lignocellulosic material or esterified cellulose material formed by adding a polybasic acid anhydride to the hydroxyl groups of a lignocellulosic material or cellulose material; an oligoesterified lignocellulosic material or oligoesterified cellulose material formed by adding a polybasic acid anhydride and a monoepoxy compound to the hydroxyl groups of a lignocellulosic material or cellulose material; or an oligoesterified lignocellulosic material or oligoesterified cellulose material formed by adding a polybasic acid anhydride and a polyhydric alcohol to the hydroxyl groups of a lignocellulosic material or cellulose material.

[0033] Examples of polybasic acid anhydrides include maleic anhydride, succinic anhydride, phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, dichloromaleic anhydride, itaconic anhydride, tetrabromophthalic anhydride, HET anhydride, trimellitic anhydride, and pyromellitic anhydride. Of these, maleic anhydride, succinic anhydride, and phthalic anhydride are particularly preferred because they are industrially advantageous and inexpensive.

[0034] The monoepoxy compound may be any compound containing one epoxy group in the molecule, and examples thereof include phenyl glycidyl ether, allyl glycidyl ether, styrene oxide, octylene oxide, methyl glycidyl ether, butyl glycidyl ether, and cresyl glycidyl ether.

[0035] Examples of polyhydric alcohols include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, pinacol, hydrobenzoin, benzpinacol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol, glycerin, and polyethylene glycol 400.

[0036] A typical method for carrying out the esterification is to mix the polybasic acid anhydride (or the polybasic acid anhydride and the monoepoxy compound, or the polybasic acid anhydride and the polyhydric alcohol) in the presence of a lignocellulosic material or a cellulosic material, and react them at a temperature of 60 to 150°C for 0.5 to 8 hours.

[0037] In the case of a reaction in which the polybasic acid anhydride and the monoepoxy compound are alternately added and esterified to hydroxyl groups in a lignocellulosic or cellulosic material, the reaction proceeds sufficiently even in the absence of a catalyst, but a basic catalyst such as sodium carbonate, dimethylbenzylamine, tetramethylammonium chloride, or pyridine may be used to promote the reaction. An addition esterification catalyst may also be used.

[0038] From the viewpoint of ease of use and effectiveness, the molecular weight of the oligomer of the polybasic acid anhydride and the monoepoxy compound is preferably about 20 to 1000 (with a degree of polymerization of preferably 5 or less, including 1), which allows the oligomer to be liquid.

[0039] The blending amounts of the polybasic acid anhydride and the monoepoxy compound are as follows: The polybasic acid anhydride is preferably used in an amount of 5 to 120 parts by mass, more preferably 10 to 100 parts by mass, per 100 parts by mass of dried lignocellulosic or cellulosic material. The monoepoxy compound preferably contains 0.5 to 2.0 epoxy equivalents per equivalent of anhydride groups in the polybasic acid anhydride used. Using 120 parts by mass or less of the polybasic acid anhydride per 100 parts by mass of dried lignocellulosic or cellulosic material is preferred because it maintains the content of the lignocellulosic or cellulosic material and inhibits exudation during thermo-compression molding. Using 5 parts by mass or more ensures thermo-compression flowability and facilitates the production of uniform molded products.

[0040] In the case of a reaction in which the polybasic acid anhydride and the polyhydric alcohol are alternately added to and esterified with the hydroxyl groups of a lignocellulose-based material or a cellulosic material, the monoepoxy compound may be replaced with the polyhydric alcohol.

[0041] Specific examples of starch-based materials that can be widely used include rice, wheat, corn, sugarcane, potato, sweet potato, tapioca, corn starch, potato starch, potato starch, tapioca starch, and lightly acetylated products thereof. Any agricultural product containing starch can be used without limitation. Furthermore, these starch-based materials can be used in the general state they are stored in, or after simple pretreatment such as washing, removing starch-free parts such as the husk, or cutting them into appropriate sizes. Starch-based materials are typically obtained in granular form, and these can be used as is.

[0042] Furthermore, it is even more preferable that the starch-based material used as a raw material undergoes such a simple pretreatment followed by a gelatinization treatment as described below. Specifically, the starch constituting the starch-based material initially has a crystalline structure (β structure), but when placed in a temperature environment of 70°C or higher in the presence of an appropriate amount of moisture, this β structure breaks down and changes to an amorphous structure (α structure). This change from β structure to α structure when raw starch is heated while containing moisture is called gelatinization. The starch granules of this gelatinized material, which exhibit an α structure, are more likely to dissolve at the molecular level in the thermally flowing polypropylene resin and become finely and uniformly dispersed, compared to when they were in the β structure in their initial heated (raw) state.

[0043] Specific examples of the process for converting starch having a β structure to an α structure include heat treatments that are generally performed when starch is used for food, such as immersing the starch in water and boiling it, or steaming it with steam.

[0044] It is generally known that when starch in an amorphous α-structure is left at low temperatures while still containing moisture, it undergoes a phenomenon known as retrogradation, whereby it reverts to its original β-structure crystalline state over time. On the other hand, it is known that if moisture is removed from starch in an amorphous α-structure, the starch maintains its α-structure and does not reversibly transition to the β-structure (does not retrogradate), even when left at low temperatures for a long period of time.

[0045] Therefore, the starch-based material used as a raw material in the present invention is one in which the starch structure is an α-structure (amorphous structure), and includes both a moist state and a moist state (dehydrated). In either case, if the starch structure of the starch-based material to be blended with the polypropylene resin is an α-structure (amorphous structure), the starch molecular chains are loosened in the polypropylene resin matrix during the kneading treatment described below, and the starch becomes more easily finely divided and dispersed. This effect cannot be obtained when blending an unheated starch-based material with a β-structure (crystalline structure).

[0046] Specifically, a method for obtaining a dehydrated α-structure starch-based material involves heating the starch-based material in the presence of moisture to gelatinize it, and then reducing the pressure of the atmosphere in a vacuum device. The use of such a dehydrated α-structure starch-based material makes it possible to store the starch-based material alone for a long period of time because it is less susceptible to aging, which contributes to shortening the production period and reducing the production costs of polypropylene resin compositions.

[0047] It should be noted that the water used to convert the starch having a β structure to an α structure as described above contains dissolved trehalose. The effect of this is that, for example, when rice is used as the starch-based material, the trehalose inhibits the decomposition of the lipid components of the rice by impregnating the raw rice with an aqueous trehalose solution, thereby suppressing the deterioration over time of the polypropylene resin composition produced using the rice. The reason for this is said to be that trehalose coats the rice components and protects the fatty acids from oxidative decomposition.

[0048] Such an effect is not limited to rice but can also be exhibited by general starch-based materials, and examples of materials that have such an effect include, in addition to the above-mentioned trehalose, salt, sucrose, antioxidants, proteolysis accelerators, cellulolysis accelerators, etc. By adding these substances to water to form an α-structure starch-based material and blending it, it is possible to obtain the effect of preventing the characteristic odor, scorching, and discoloration of the produced polypropylene resin composition.

[0049] So far, we have explained that starch-based materials that have already been gelatinized are used as raw materials, but by using the production method described below, starch-based materials with a β structure that contain moisture can also be used.

[0050] Specifically, raw rice is soaked in water for a predetermined time, drained, and then placed in a kneader together with polypropylene resin and kneaded at the thermal flow temperature of the polypropylene resin. This thermal flow temperature (usually 100 to 170°C) is sufficient to transition the starch structure of the raw rice from a β structure to an α structure, so the raw rice undergoes a gelatinization process during the kneading process. After the raw rice has converted to an α structure, as described above, the starch molecular chains are loosened, refined, and dispersed into the polypropylene resin matrix.

[0051] Here, in order for raw rice with a β structure to be heated and converted to a gelatinized structure, it is desirable for the water content to be 17% by mass or more, and for this purpose, it is preferable to soak the rice in water for 5 minutes or more. Furthermore, for starch-based materials such as potatoes, which contain enough water to convert the starch to an α structure by themselves, there is no need to soak the potatoes in water as with rice, and they can be directly put into the kneader.

[0052] The biomass filler (C) is preferably one or more plant-derived fillers selected from the group consisting of wood, pulp, cellulose fiber, bamboo, sugarcane (bagasse), rice husks, and rice (starch).

[0053] The biomass filler (C) preferably has an average particle size of 5 to 300 μm, more preferably 10 to 200 μm. Within this range, secondary aggregation due to a small average particle size during kneading is unlikely to occur, and deterioration of physical properties and moldability is prevented. Furthermore, within this range, the occurrence of holes during extrusion molding or thermoforming due to a large average particle size is prevented.

[0054] Here, the average particle size is a value measured using a laser diffraction particle size distribution analyzer, and refers to the value at which the integrated value of the volume accumulation distribution is 50%. An example of the measuring device is the LA-920 model manufactured by Horiba, Ltd.

[0055] (D) Inorganic filler The inorganic filler (D) is an inorganic filler typically used in polypropylene resins, and examples thereof include talc, calcium carbonate, shirasu balloons, perlite, aluminum hydroxide, and mica. The inorganic filler (D) can reduce the burnt odor originating from the biomass filler (C) that occurs during the production of the polypropylene resin composition, and can also maintain moldability while significantly reducing the amount of polypropylene resin used. Furthermore, it can improve physical properties in the same way as when an inorganic filler is used in a typical polypropylene resin.

[0056] The inorganic filler (D) is preferably one or more inorganic fillers selected from the group consisting of talc, calcium carbonate, shirasu balloon, perlite, aluminum hydroxide, and mica.

[0057] The inorganic filler (D) preferably has a specific surface area (BET method) of 5 m 2 / g or more, more preferably 5 to 30m 2 When the specific surface area is within the above range, the effect of adsorbing and suppressing the burning odor originating from the biomass filler (C) is great.

[0058] Here, the specific surface area determined by the BET method is a value calculated from nitrogen adsorption measurement using an automatic gas adsorption amount measuring device.

[0059] The polypropylene resin composition of the present invention contains 35 to 69 mass% of polypropylene resin (A), 1 to 5 mass% of compatibilizer (B), Mc mass% of biomass filler (C), and Md mass% of inorganic filler (D), so that the total (Mc + Md) of the biomass filler (C) and the inorganic filler (D) is 30 to 60 mass% and Mc≧Md>0. Preferably, the polypropylene resin composition contains 43 to 68 mass% of polypropylene resin (A), 2 to 4 mass% of compatibilizer (B), and the total (Mc + Md) of the biomass filler (C) and the inorganic filler (D) is 30 to 55 mass%.

[0060] If the polypropylene resin (A) content is less than 35% by mass, the fluidity of the composite material is significantly reduced, making molding impossible. Furthermore, if it exceeds 69% by mass, the biomass content, a feature of the present invention, decreases, further reducing the effect of improving physical properties. If the compatibilizer (B) content is less than 1% by mass, the affinity between the polypropylene resin (A) and the biomass filler (C) decreases, making the biomass filler (C) more likely to aggregate, leading to a deterioration in physical properties. Furthermore, if it exceeds 5% by mass, the drawbacks of the compatibilizer (B), such as coloration, odor, and burning, become more pronounced. Furthermore, since the physical properties of the compatibilizer (B) itself are generally worse than those of the polypropylene resin (A), these drawbacks become more pronounced. Furthermore, since the compatibilizer (B) generally has high fluidity, it also deteriorates the moldability and thermoformability of the extruded sheet.

[0061] If the total (Mc+Md) of the biomass filler (C) and the inorganic filler (D) is less than 30% by mass, no effect can be expected in terms of reducing the amount of plastic used, and if it exceeds 60% by mass, moldability and fluidity will deteriorate.

[0062] The inorganic filler (D) content Md and the biomass filler (C) content Mc satisfy the relationship Mc≧Md>0. Preferably, the relationship 5×Md≧Mc≧1.2×Md>0 is satisfied. Within the above range, shear heat generation during kneading is suppressed, odor due to burning of the biomass filler can be further reduced, and the appearance of molded articles of the polypropylene resin composition can be further improved. Note that, as is clear from the above-mentioned relationship, the biomass filler (C) content Mc and the inorganic filler (D) content Md are both greater than 0.

[0063] (E) Thermoplastic elastomer The polypropylene resin composition may optionally contain a thermoplastic elastomer (E). Examples of the thermoplastic elastomer (E) include olefin-based elastomers, styrene-based elastomers, etc. These may be used alone or in combination of two or more.

[0064] Examples of olefin-based elastomers include ethylene-propylene copolymer elastomers (EPR), ethylene-butene copolymer elastomers (EBR), ethylene-hexene copolymer elastomers (EHR), ethylene-octene copolymer elastomers (EOR), ethylene-α-olefin-diene terpolymer elastomers such as ethylene-propylene-ethylidenenorbornene copolymer, ethylene-propylene-butadiene copolymer, and ethylene-propylene-isoprene copolymer, and hydrogenated polymer elastomers such as ethylene-ethylene-butylene-ethylene copolymer (CEBC). Among these, ethylene-propylene copolymer elastomers, ethylene-butene copolymer elastomers, and ethylene-hexene copolymer elastomers are preferred.

[0065] Examples of styrene-based elastomers include styrene-butadiene-styrene triblock copolymer elastomer (SBS), styrene-isoprene-styrene triblock copolymer elastomer (SIS), styrene-ethylene-butylene copolymer elastomer (SEB), styrene-ethylene-propylene copolymer elastomer (SEP), styrene-ethylene-butylene-styrene copolymer elastomer (SEBS), styrene-ethylene-butylene-ethylene copolymer elastomer (SEBC), hydrogenated styrene-butadiene elastomer (HSBR), styrene-ethylene-propylene-styrene copolymer elastomer (SEPS), styrene-ethylene-ethylene-propylene-styrene copolymer elastomer (SEEPS), styrene-butadiene-butylene-styrene copolymer elastomer (SBBS), partially hydrogenated styrene-isoprene-styrene copolymer elastomer, and partially hydrogenated styrene-isoprene-butadiene-styrene copolymer elastomer.

[0066] The thermoplastic elastomer (E) preferably has an MFR of 0.1 to 10 g / 10 min, measured at 190°C under a load of 2.16 kg. If the thermoplastic elastomer (E) has an MFR of 0.1 g / 10 min or more, the load on the extruder is reduced during extrusion molding of a sheet, improving productivity. Furthermore, if the MFR is 10 g / 10 min or less, the melt tension of the sheet can be maintained high, and the molded product will not sag under its own weight during extrusion molding or thermoforming, which is preferable.

[0067] The amount of thermoplastic elastomer (E) added is preferably 1 to 50 parts by mass, more preferably 3 to 30 parts by mass, and even more preferably 5 to 15 parts by mass, per 100 parts by mass of the total of (A) to (D). When the amount added is within the above range, the balance of physical properties is improved.

[0068] The polypropylene resin composition may contain various additives as optional components, as needed, such as nucleating agents, heat stabilizers, antioxidants, weather stabilizers, light stabilizers, UV absorbers, antistatic agents, slip agents, antiblocking agents, antifogging agents, neutralizing agents, metal deactivators, surfactants, colorants, antibacterial and antifungal agents, flame retardants, plasticizers, dispersants, conductive agents, preservatives, fragrances, deodorizers, insect repellents, etc. Two or more of these optional components may be used in combination.

[0069] The propylene resin composition can be prepared by dry blending or mixing powdered or pelletized polypropylene resin (A), compatibilizer (B), biomass filler (C), inorganic filler (D), and other optional compounding ingredients using a Henschel mixer or similar. Depending on the circumstances, the biomass filler (C) and inorganic filler (D) may be preliminarily bonded to the polypropylene resin (A) and compatibilizer (B) using a gelation method or similar. These may also be kneaded in a single-screw or twin-screw extruder, or kneaded to a high filler content to form a masterbatch, which is then diluted to the required concentration during molding.

[0070] The polypropylene resin composition can be produced by mixing polypropylene resin (A), compatibilizer (B), biomass filler (C), and inorganic filler (D), or polypropylene resin (A), compatibilizer (B), biomass filler (C), inorganic filler (D), and thermoplastic elastomer (E), along with optional components blended as needed, or by heating and kneading them using a single-screw extruder, twin-screw extruder, etc. The resin temperature for heating and kneading is preferably in the range of 100°C to 300°C and can be appropriately determined taking into consideration the load on the kneading, the color and odor of the resin composition, etc.

[0071] The polypropylene resin composition can be molded into a desired shape to produce various molded articles by means of pressure molding, film molding, vacuum molding, extrusion molding, injection molding, etc. The molding temperature can be set appropriately within the range of 100°C to 300°C, taking into consideration the load of kneading, the color and odor of the resin composition, etc.

[0072] The polypropylene resin composition can be effectively used as a material for various film and sheet materials, disposable molded products (e.g., containers, pipes, timber, rods, artificial wood, trays, concrete panels, foams, etc.), furniture, building materials, automotive interior and exterior materials, chassis and housings for home appliances, civil engineering and construction materials, agricultural, dairy and fishery materials, recreational materials, sports materials, etc.

[0073] The polypropylene resin composition is also suitably used in the fields of electrical insulating materials, industrial parts and materials, building materials, etc., and is particularly suitably used as a raw material for housing components, building materials, and home appliances. Specific examples include trays, tableware, speakers, bathroom unit floor pans, buckets, toilet seats, cabinets, stereo cabinets, baseboards, door materials, counter materials, window frames, soundproofing boards, shelves, civil engineering timber, pillars, structural materials, kitchen components, floors, baths, underlayment boards, piano organ main boards, and building and ceiling materials.

[0074] According to the polypropylene resin composition of the present invention, the amount of polypropylene resin produced from fossil fuels used can be reduced while maintaining physical properties such as rigidity, and as a result, carbon dioxide emissions from the material can be reduced. [Example]

[0075] The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples.

[0076] 1. Evaluation Method (1) Pellet odor 100 g of pellets were weighed and placed in a 500 ml glass container. After storing at 80°C for 3 hours, the lid of the glass container was opened and the odor of the pellets inside was evaluated sensorily. The odor intensity was evaluated by five panelists, who assigned points according to the following criteria, and the average of the five panelists' scores was used as the result. 1: The smell is so strong that it is unbearable 2: It smells very strong. I can clearly tell what kind of smell it is. 3: I can clearly tell what the smell is, but it's not painful. 4: If you smell it carefully, you'll know what kind of smell it is. 5: Almost no smell. Only a faint smell.

[0077] (2) Moldability of extruded sheet moldings and thermoformed products The pellets were placed in an extruder with a 40 mm screw diameter, extruded through a T-die at a resin temperature of 190°C, sandwiched between mirror-finished metal casting rolls with a surface temperature of 60°C, and continuously taken up at a speed of 1.0 m / min while being cooled and solidified, to obtain a polypropylene resin composition sheet 400 mm wide and 0.8 mm thick. The moldability of the extrusion sheet molding was evaluated as follows. ○: Good sheet forming. Appearance is also beautiful. △: Sheets can be formed, but surface roughness and other appearance defects can be observed. ×: Sheet molding is not possible (cannot be shaped)

[0078] The resulting sheet was then cut into 40cm x 40cm pieces and heated on both sides with upper and lower heaters (80% output) using a multipurpose thermoforming machine (manufactured by Asano Laboratory Co., Ltd.). Containers were then thermoformed by vacuum and pressure forming using a cup-shaped deep-draw mold with an upper inner diameter of 10.8cm and a depth of 8cm. The heating time was varied over a range of 18 to 32 seconds, with eight settings at 2-second intervals.

[0079] The moldability of the thermoformed product was evaluated based on (i) the range of heating times over which the product can be thermoformed, and (ii) the appearance of the container. The moldability was judged as follows: (i) Wide range of heating times for thermoforming ◎: The container shape can be reproduced (can be shaped to the container shape) with a heating time of 3 levels or more ○: Two levels of heating time that can reproduce the container shape △: The heating time required to reproduce the container shape is level 1. ×: The container shape cannot be reproduced for all heating times (ii) Appearance of the container (visual inspection) ○: No irregularities or patterns can be seen on the surface △: Slight irregularities or patterns can be seen on the surface ×: Unevenness or patterns can be clearly seen on the surface

[0080] (3) Flexural modulus The pellets were injection molded at a resin temperature of 200°C into a shape specified in JIS K7171, and the flexural modulus was measured at a test temperature of 23°C in accordance with JIS K7171 using test pieces.

[0081] 2. Raw materials The raw materials used for the evaluation are as follows: The physical properties of the raw materials are summarized in Table 1. Polypropylene resin (A-1): Propylene-ethylene block copolymer, Japan Polypropylene Waymax (registered trademark) EX4000, MFR 6.0 g / 10 min, melt tension 4 cN Compatibilizer (B-1): Acid-modified low molecular weight polypropylene, Sanyo Chemical Industries, Ltd., Umex (registered trademark) 1001, acid value (JIS K 0070) 26 mg KOH / g, molecular weight Mw 45,000 -Biomass filler (C-1): Casino wood flour (100 mesh), average particle size 150 μm - Inorganic filler (D-1): Talc, PC25RC manufactured by Nippon Talc Co., Ltd., specific surface area (BET method) 7m 2 / g, average particle size 5.7μm - Inorganic filler (D-2): Calcium carbonate, MSK-PO manufactured by Maruo Calcium Co., Ltd., specific surface area (BET method) 10m 2 / g, average particle size 0.15μm Thermoplastic elastomer (E-1): Toughmer (registered trademark) A0550S manufactured by Mitsui Chemicals, Inc., MFR 1.0 g / 10 min, density 0.860 g / cm 3

[0082] [Table 1]

[0083] (Examples 1 to 5, Comparative Examples 1 to 7) Eight types of polypropylene resin compositions (Examples 1 to 5, Comparative Examples 1 to 7) shown in Table 1 were weighed and uniformly mixed by stirring using a ribbon blender. The resulting mixture was fed into a twin-screw extruder with a screw diameter of 15 mm, kneaded at a resin temperature of 190°C, extruded into strands, cooled with water, and pelletized to obtain polypropylene resin compositions.

[0084] The odor of the resulting polypropylene resin composition pellets, the moldability of extrusion sheet molding and thermoforming products, and the flexural modulus of the injection-molded products were evaluated by the methods described above. The evaluation results are summarized in Table 1.

Claims

1. The polypropylene resin composition is characterized by comprising 43% by mass to 69% by mass of polypropylene resin (A), 1% by mass to 3% by mass of compatibilizer (B), Mc% by mass of biomass filler (C), and Md% by mass of inorganic filler (D), wherein the total (Mc+Md) of the biomass filler (C) and the inorganic filler (D) is 30 to 55% by mass and Mc≧Md>0 is satisfied, and further comprising 1 to 50 parts by mass of thermoplastic elastomer (E) per 100 parts by mass of the total of 100% by mass of the polypropylene resin (A), compatibilizer (B), biomass filler (C), and inorganic filler (D).

2. 2. The polypropylene resin composition according to claim 1, wherein the polypropylene resin (A) is at least one selected from the group consisting of a propylene homopolymer, a propylene-ethylene block copolymer, and a propylene-ethylene-1-butene block copolymer.

3. 3. The polypropylene resin composition according to claim 1, wherein the biomass filler (C) is at least one plant-derived filler selected from the group consisting of wood, pulp, cellulose fiber, bamboo, sugarcane (bagasse), rice husks, and rice (starch).

4. The polypropylene resin composition according to any one of claims 1 to 3, wherein the inorganic filler (D) is at least one selected from the group consisting of talc, calcium carbonate, shirasu balloons, perlite, aluminum hydroxide, and mica.

5. The polypropylene resin composition according to any one of claims 1 to 4, characterized in that the biomass filler (C) has an average particle size of 5 to 300 µm.

6. The specific surface area (BET method) of the inorganic filler (D) is 5 m ２ The polypropylene resin composition according to any one of claims 1 to 5, wherein the polypropylene resin composition has a viscosity of 1 / g or more.

7. The polypropylene resin composition according to any one of claims 1 to 6, characterized in that it contains 10 to 50 parts by mass of the thermoplastic elastomer (E).

8. A polypropylene resin composition described in any one of claims 1 to 7, characterized in that the melt flow rate (MFR) of the thermoplastic elastomer (E) measured at 190°C under a load of 2.16 kg is 0.1 to 10 g / 10 min.

9. An extrusion molded product, an injection molded product, a thermoformed product, or a blow molded product comprising the polypropylene resin composition according to any one of claims 1 to 8.

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