A biodegradable resin composition containing a polyolefin-containing resin, a cellulose-based compound, and an organic acid metal salt; a molded article containing the same; a method for producing the same; and a method for producing a biodegradable resin composition.

Abstract

To provide a resin composition containing a polyolefin which has sufficient strength and thermal degradability or biodegradability and has high processability as general-purpose plastic.SOLUTION: A degradable resin composition contains a polyolefin-containing resin, a cellulosic compound, and an organic acid metal salt. A molding can be provided which has sufficient strength as general-purpose plastic before heating for degradation but which allows the polyolefin-containing resin to be degraded by the heating for degradation.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a biodegradable resin composition containing a polyolefin-containing resin, a cellulosic compound, and an organic acid metal salt, a molded article containing the same, a method for producing the same, and a method for producing a biodegradable resin composition. [Background technology]

[0002] General-purpose plastics, including polyolefins such as polyethylene and polypropylene, are widely used in food packaging and agriculture in the form of films and sheets. Because these general-purpose plastics are used in various forms, unlike PET bottles, recycling is extremely difficult, and they are often incinerated. However, incineration requires a large amount of thermal energy. Furthermore, if left in the soil as waste for extended periods without collection, polyolefins are extremely difficult to decompose by microorganisms, leading to environmental damage to the soil. Therefore, there is a need for resin compositions containing polyolefins that can be broken down to a low molecular weight in soil and compost, and then decomposed into water and carbon dioxide by microorganisms.

[0003] Patent Document 1 discloses a method for manufacturing plastic tableware in which 85% to 70% polypropylene is mixed with 30% to 15% biodegradable additives and molded together, thereby achieving practicality as commercial tableware while decomposing upon exposure to heat or leaving it in soil. However, this method requires a high amount of biodegradable additives (15% or more), which are more expensive than polypropylene, making it difficult to produce inexpensive material and impractical for use as a general-purpose plastic. Furthermore, the effect is not easily obtained with small amounts of biodegradable additives, making it unsuitable for rapid decomposition.

[0004] Patent documents 2 and 3 disclose a resin composition comprising a starch-derived biomass material, a polyolefin resin, and an oxidative decomposition accelerator. However, while the incorporation of starch into a polyolefin resin is advantageous in terms of thermal decomposition or biodegradability due to the properties of amylose contained in starch, its structure results in insufficient strength as a general-purpose plastic, thus limiting its applications.

[0005] Patent Document 4 discloses a cellulose fiber resin molded article obtained by dispersing cellulose fibers in a thermoplastic resin that is a polyolefin. However, although this material can be obtained with sufficient strength as a general-purpose plastic, it has poor thermal decomposition or biodegradability and was not suitable for decomposition in soil. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2000-312638 [Patent Document 2] Japanese Patent Publication No. 2020-122111 [Patent Document 3] Japanese Patent Publication No. 2009-227777 [Patent Document 4] Japanese Patent Publication No. 2020-193262 [Overview of the project] [Problems that the invention aims to solve]

[0007] Conventional technologies have failed to produce resin compositions containing polyolefins that possess sufficient strength, thermal decomposition or biodegradability, and high processability for general-purpose plastics, even with the addition of small amounts of oxidative decomposition accelerators.

[0008] The present invention has been made to solve the aforementioned problems and aims to provide a degradable resin composition that has sufficient mechanical properties, excellent thermal decomposition or biodegradability, and can be easily reduced to a low molecular weight, a molded article containing the same, a method for producing the same, and a method for producing decomposition products of the degradable resin composition. [Means for solving the problem]

[0009] The present inventors have diligently studied the aforementioned problems and arrived at the present invention. That is, the object of the present invention is achieved by a biodegradable resin composition comprising a polyolefin-containing resin, a cellulosic compound, and an organic acid metal salt.

[0010] The polyolefin used in the biodegradable resin composition of the present invention is preferably selected from the group consisting of low-density polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene, chlorinated polyethylene, polytetrafluoroethylene, ethylene-α-olefin copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, polypropylene, chlorinated polypropylene, and polymethylpentene.

[0011] The polyolefin used in the biodegradable resin composition of the present invention is preferably polypropylene or a propylene-ethylene copolymer.

[0012] The organic acid of the organic acid metal salt used in the biodegradable resin composition of the present invention is C6-C 22 aliphatic carboxylic acids and C6-C 22 It is preferable to select from the group consisting of aromatic carboxylic acids.

[0013] The carboxylic acid used in the biodegradable resin composition of the present invention is preferably a monocarboxylic acid.

[0014] The metal of the metal organic acid salt used in the degradable resin composition of the present invention is preferably selected from the group consisting of aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, tin, lanthanum, cerium, tungsten, antimony, and bismuth.

[0015] The cellulose-based compound used in the degradable resin composition of the present invention is preferably contained in an amount of 1 to 60 parts by mass with respect to 100 parts by mass of the resin containing the polyolefin.

[0016] The metal organic acid salt used in the degradable resin composition of the present invention is preferably contained in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the resin containing the polyolefin.

[0017] The present invention also relates to a molded body containing the composition of the present invention.

[0018] The present invention also relates to a method for producing the molded body of the present invention, which includes a step of kneading a resin containing polyolefin, a cellulose-based compound, and a metal organic acid salt.

[0019] The present invention also relates to a method for producing a decomposition product of a degradable resin composition, which includes a step of heating a degradable resin composition containing a resin containing polyolefin, a cellulose-based compound, and a metal organic acid salt at 40°C to 100°C.

[0020] In the method for producing a decomposition product of the degradable resin composition of the present invention, it is preferable to perform heating for 1 week to 6 months.

Advantages of the Invention

[0021] According to the degradable resin composition of the present invention, it has sufficient strength as a general-purpose plastic before heating for decomposition, while a molded body in which the resin containing polyolefin can be decomposed can be provided by heating for decomposition.

[0022] The present invention provides a method for producing decomposition products of a degradable resin composition, in which a resin containing polyolefin is decomposed by heating and transformed into low-molecular-weight decomposition products that can be sufficiently decomposed by microorganisms and the like. [Modes for carrying out the invention]

[0023] [Degradable resin composition] The biodegradable resin composition of the present invention will now be described in detail. The biodegradable resin composition of the present invention is characterized by comprising a resin containing a polyolefin, a cellulosic compound, and an organic acid metal salt.

[0024] In this invention, "degradability" means that the material can be decomposed by heat or microorganisms.

[0025] [Resins containing polyolefins] In one embodiment, the polyolefin is C2-C 12 It may be at least one homopolymer, copolymer, or terpolymer selected from olefin monomers.

[0026] C2~C 12 The olefin monomer has one or more double bonds C2-C 12 Alkenes in which hydrogen is a halogen such as fluorine, chlorine, or bromine, or C1-C 18 It may be substituted with an alkyl group. Preferably, it may be selected from the group consisting of ethylene, propylene, butene, pentene, hexene, heptene, octene, decene, undecene, dodecene, and tetrafluoroethylene, and more preferably ethylene and propylene.

[0027] In one embodiment, the polyolefin is C2-C 12 This may be a copolymer or terpolymer of an olefin monomer and another monomer copolymerizable with the olefin monomer.

[0028] Other monomers copolymerizable with olefin monomers are not particularly limited, but include vinyl chloride, vinyl acetate, vinyl alcohol, styrene, alpha-methylstyrene, C1-C1 18 The group may be selected from alkyl (meth)acrylates and (meth)acrylic acids.

[0029] In one embodiment, the copolymer and terpolymer may be random polymers, block polymers, or graft polymers, and are preferably random polymers.

[0030] In one embodiment, the polyolefin may be selected from the group consisting of low-density polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene, chlorinated polyethylene, polytetrafluoroethylene, ethylene-α-olefin copolymers such as propylene-ethylene copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, polypropylene, chlorinated polypropylene, and polymethylpentene.

[0031] Preferably, the polyolefin may be low-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer, or polypropylene, more preferably polypropylene or propylene-ethylene copolymer, and even more preferably polypropylene.

[0032] In one embodiment, the weight-average molecular weight of the polyolefin may be 20,000 g / mol to 1,000,000 g / mol, preferably 50,000 g / mol to 750,000 g / mol, and more preferably 100,000 g / mol to 500,000 g / mol. If the weight-average molecular weight of the polyolefin is 20,000 g / mol or less, sufficient strength cannot be obtained in the molded article containing the biodegradable resin composition, and if the weight-average molecular weight of the polyolefin is 1,000,000 g / mol or more, the processability of the molded article containing the biodegradable resin composition is poor.

[0033] The measurement of the weight-average molecular weight of polyolefins is not particularly limited, but high-temperature gel permeation chromatography may be used, and it may be calculated from a calibration curve of polystyrene standards.

[0034] In one embodiment, the resin containing the polyolefin may contain 80% by mass or more and 100% by mass or less of the polyolefin, preferably 90% by mass or more and 100% by mass or less, and more preferably 95% by mass or more and 100% by mass or less.

[0035] [Cellulose compounds] In one embodiment, the cellulose used in the cellulosic compound is a linear polymer in which hydroxyl groups in glucose are β-1,4 condensed, and is produced from natural materials such as wood and cotton by conventional physical or chemical methods. The cellulosic compound may be crystalline cellulose, microcrystalline cellulose, spherical cellulose, powdered cellulose, cellulose microfibrils, cellulose nanofibrils, cellulose microfibers, cellulose nanocrystals, or cellulose nanofibers, and is preferably cellulose nanofibers. Because the cellulosic compound is cellulose nanofiber, it can be uniformly dispersed in the biodegradable resin composition.

[0036] In one embodiment, the cellulosic compound can be selected from cellulose and cellulose derivatives. A cellulose derivative may be one in which at least one of the three hydroxyl groups contained in the glucose unit of cellulose has been chemically modified. For example, it may be alkylated with a methyl group or ethyl group, hydroxyalkylated with a hydroxymethyl group, hydroxyethyl group or hydroxypropyl group, carboxyalkylated with a carboxymethyl group, acylated with an acetyl group, propionyl group or butyryl group, carboxylated, nitrated, phosphate esterified, phosphite esterified, xantate esterified, sulfurized, alkoxysilaneized with an amino group or epoxy group, carbamate, carboxyl-based N-acylurea, carboxyl-based alkylammonium, fluorene derivatization, or phthalimidization. Furthermore, cellulose derivatives that have been hydroxyalkylated, carboxyalkylated, carboxylated, nitrated, phosphate esterified, phosphite esterified, xantate esterified, and sulfurized may form metal salts.

[0037] In one embodiment, the cellulose compound may be dispersed in a resin containing a polyolefin. The resin containing the polyolefin in which the cellulose is dispersed may be one of the polyolefin-containing resins exemplified above, and is preferably polypropylene. By dispersing the cellulose compound in a polyolefin, the cellulose compound can be uniformly dispersed in the biodegradable resin composition.

[0038] In one embodiment, the cellulose compound may be present in 1 to 60 parts by mass per 100 parts by mass of the resin containing the polyolefin. Preferably, it may be present in 2 to 50 parts by mass, and more preferably, 4 to 45 parts by mass per 100 parts by mass of the resin containing the polyolefin.

[0039] [Organic acid metal salts] In one embodiment, the organic acid of the organic acid metal salt may be an acid having a molecular structure composed of carbon atoms and having at least one functional group selected from the group consisting of a carboxy group, a sulfonic acid group, or a phosphonic acid group.

[0040] Examples of the organic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, docosahexaenoic acid, acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, benzoic acid, phthalic acid, cinnamic acid, trimellitic acid, glycolic acid, lactic acid, tartronic acid, glyceric acid, hydroxybutyric acid, malic acid, tartaric acid, citramalic acid, citric acid, isocitric acid, pyruvic acid, oxaloacetic acid, α-ketoglutaric acid, acetoacetic acid, acetonedicarboxylic acid, levulinic acid, β-chloropropionic acid, nicotinic acid, ascorbic acid, hydroxypivalic acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, methylphosphonic acid, phenylphosphonic acid, and the like.

[0041] In one embodiment, the organic acid of the organic acid metal salt may be selected from the group consisting of aliphatic carboxylic acids having C6 to C 30 and aromatic carboxylic acids having C6 to C 30 . Preferably, it is an aliphatic carboxylic acid having C 12 to C 22 , more preferably, a saturated aliphatic carboxylic acid having C 12 to C 22 .

[0042] In one embodiment, the carboxylic acid is preferably a monocarboxylic acid. Preferably, it is C 12 to C 22The saturated aliphatic monocarboxylic acid may be selected from the group consisting of lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, and behenic acid, with stearic acid being particularly preferred.

[0043] In one embodiment, the metal of the organic acid metal salt may be a redox-capable metal selected from the group consisting of aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, tin, lanthanum, cerium, tungsten, antimony, and bismuth. More preferably, it may be selected from the group consisting of manganese, iron, cobalt, copper, zinc, and cerium, and particularly preferably, it may be selected from the group consisting of manganese and cerium.

[0044] In one embodiment, the organic acid metal salt may be selected from the group consisting of manganese stearate, iron stearate, cobalt stearate, copper stearate, zinc stearate, and cerium stearate, and preferably selected from the group consisting of manganese stearate and cerium stearate.

[0045] The organic acid metal salt of the present invention acts as an oxidative decomposition accelerator in a decomposable composition, promoting the thermal decomposition of the composition. While the thermal decomposition effect is weak when only an organic acid metal salt is blended with polyolefin, the thermal decomposition can be significantly accelerated by blending a cellulose-based compound with the decomposable composition.

[0046] In one embodiment, the organic acid metal salt may be dispersed in a resin containing a polyolefin. The resin containing the polyolefin in which the organic acid metal salt is dispersed may be any of the polyolefin-containing resins exemplified above, and is preferably polypropylene. Because the organic acid metal salt is dispersed in the polyolefin, it can be uniformly dispersed in the biodegradable resin composition and thus decomposed efficiently.

[0047] In one embodiment, the organic acid metal salt may be present in an amount of 0.1 to 10 parts by mass per 100 parts by mass of the resin containing the polyolefin. Preferably, it may be present in an amount of 0.5 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and even more preferably 0.8 to 2 parts by mass per 100 parts by mass of the resin containing the polyolefin.

[0048] [Molded body] The present invention also relates to a molded article comprising the composition of the present invention.

[0049] In one embodiment, the molded article of the present invention may be a sheet, a film, or a molded article of various shapes. The thickness of the sheet or film is not particularly limited, but may be 10 μm to 10 mm, and preferably 0.5 mm to 5 mm.

[0050] [Method for manufacturing molded products] The present invention also relates to a method for producing a molded article of the present invention, comprising the step of kneading a resin containing a polyolefin, a cellulosic compound, and an organic acid metal salt.

[0051] In one embodiment, the step of kneading a resin containing polyolefin, a cellulosic compound, and an organic acid metal salt may be performed using a Henschel mixer, a three-roll mixer, a two-roll mixer, a kneader, a Banbury mixer, an extruder, or other kneader. Preferably, the mixture may be melt-kneaded at a temperature of 120°C to 250°C. By melt-kneading, the components of the biodegradable resin composition can be uniformly dispersed in the polyolefin matrix.

[0052] In one embodiment, the method for producing a molded article of the present invention may include a step of molding a kneaded biodegradable composition, or the biodegradable composition may be molded by dry blending without melt kneading.

[0053] In one embodiment, the molding process can produce a molded body of a desired shape, thickness, and size from a kneaded material using conventional molding methods such as extrusion molding, injection molding, calendering, blow molding, press molding, inflation molding, vacuum molding, rolling molding, casting, and foam molding.

[0054] [Method for producing decomposition products of biodegradable resin compositions] The present invention also relates to a method for producing decomposition products of a decomposition resin composition, comprising the step of heating the decomposition resin composition, which includes a polyolefin-containing resin, a cellulosic compound, and an organic acid metal salt, at 40°C to 100°C.

[0055] In one embodiment, the biodegradable resin composition used in the production of the decomposition product may be the biodegradable resin composition described above.

[0056] In one embodiment, the temperature of the heating step may be 40°C to 100°C, preferably 60°C to 90°C, and more preferably 70°C to 85°C. If the temperature is lower than 40°C, the rate at which the polyolefin-containing resin in the biodegradable resin composition decomposes is slow, and the molecular weight of the polyolefin-containing resin does not decrease significantly, so the strength is maintained. If the temperature is higher than 100°C, the polyolefin in the biodegradable resin composition may melt.

[0057] In one embodiment, the heating process may be carried out for 1 week to 6 months. More preferably, it may be carried out for 1 month to 4 months, and more preferably, for 1 month to 3 months.

[0058] In one embodiment, the decomposition of the biodegradable resin composition may be confirmed by the weight-average molecular weight of the polyolefin in the decomposition product, the change in the weight of the biodegradable resin composition, and the change in the maximum tensile strength of the biodegradable resin composition. Alternatively, the decomposition of the biodegradable resin composition may be confirmed by a dumbbell-shaped test piece obtained by injection molding.

[0059] In one embodiment, the weight-average molecular weight of the polyolefin in the decomposition product may be 100 g / mol to 10,000 g / mol, preferably 100 g / mol to 8,000 g / mol, and more preferably 100 g / mol to 5,000 g / mol.

[0060] In one embodiment, the weight of the decomposition product may decrease by 0.8% to 80% after heating for decomposition. Preferably, it may be 1.0% to 50%, and more preferably 1.5% to 30%.

[0061] In one embodiment, the maximum tensile strength of the decomposition product may decrease by 40% to 100% after heating for decomposition, preferably 50% to 100%, and more preferably 60% to 100%.

[0062] The present invention will be described below with reference to examples, but the present invention is not limited thereto. [Examples]

[0063] The following samples were used in the examples. [sample] • Polyolefins Nippon Polypropylene Co., Ltd. "Novatec FL203D" Film Grade (MFR=3): Polypropylene • Cellulose compounds Daio Paper Corporation's "ELLEX-R55": 55% cellulose-containing polypropylene resin masterbatch pellets • Organic acid metal salts P-Life PP20, manufactured by P-Life Japan Inc.: Polypropylene resin masterbatch pellets containing 20% ​​by mass of organic acid metal salts.

[0064] [Example 1] A pellet material was prepared by blending three types of materials to make a composition of 94% by mass of polypropylene, 5% by mass of cellulosic compounds, and 1% by mass of organic acid metal salts. This mixture was placed in a polyethylene bag, dry-blend, and then injection-molded using a small injection molding machine (AE-M3, manufactured by Shinko Cellbic Co., Ltd.) to produce small dumbbells (ISO 527-2-7). The molding machine temperature was set to 220°C and the mold temperature to 50°C.

[0065] [Reference Example 1, Examples 2 and 3, and Comparative Examples 1-8] A small dumbbell was created using the same procedure as in Example 1, except that the ingredients were blended as shown in Tables 1-3 below.

[0066] <Testing Method> (Time-lapse testing) The small dumbbells that were created were heat-treated in an 80°C constant temperature chamber of an ESPEC oven for a specified time, and then left at room temperature overnight before each test was conducted.

[0067] (Weight-average molecular weight, number-average molecular weight, and molecular weight distribution) The values ​​were calculated from the calibration curve of a polystyrene standard using high-temperature gel permeation chromatography (Tosoh Corporation "HLC8121GPC / HT", 135°C, eluent: o-dichlorobenzene).

[0068] (Changes in weight loss over time) The weight of the small dumbbells after heat treatment was measured using a precision electronic balance, and the weight reduction rate relative to the weight of the small dumbbells before heat treatment was calculated.

[0069] (Maximum tensile strength) The maximum tensile strength (yield strength or breaking strength) of a small dumbbell after heat treatment was measured using a tensile testing apparatus (Shimadzu AG-X, tensile speed 20 mm / min).

[0070] The formulation and test results are shown in Tables 1-3.

[0071] [Table 1]

[0072] [Table 2]

[0073] [Table 3]

[0074] Comparing Examples 1-3 and Reference Example 1, Comparative Examples 1, 2, and 4 in Table 1, Examples 1-3 show a significant decrease in weight-average molecular weight after one month of heating. Furthermore, comparing Examples 1-3 and Comparative Examples 3, 5, and 6, the weight-average molecular weight does not decrease significantly when neither the cellulose-based compound nor the organic acid metal salt is present. From these results, it can be seen that the decomposition of polypropylene is significantly accelerated by incorporating cellulose-based compounds and organic acid metal salts.

[0075] In Comparative Example 7 in Table 2, the polypropylene resin did not undergo thermal decomposition and showed no weight change without the addition of cellulosic compounds and organic acid metal salts. Comparing Examples 1-3 with Comparative Examples 3 and 8, only Examples 1-3 showed a weight decrease after one month, indicating that thermal decomposition was accelerated in Examples 1-3. Furthermore, Comparative Examples 5 and 6 showed almost no weight change after one to four months, indicating that decomposition was not progressing.

[0076] Table 3 also shows similar results to Table 2, with the maximum tensile strength of Examples 1-3 after one month being 36% or less of the pre-heat treatment level, while the maximum tensile strength of Comparative Examples 3 and 8 after one month remained unchanged from before the heat treatment, thus confirming the thermal decomposition accelerating effect of Examples 1-3. Furthermore, comparing Examples 1-3 with Comparative Example 7, the pre-heat treatment maximum tensile strengths are similar or higher, indicating that they can be used for general polypropylene applications. [Industrial applicability]

[0077] The molded articles of the present invention are suitable as materials that can be easily decomposed by microorganisms in soil, as they have excellent processability and strength as general-purpose plastics, and their molecular weight and weight can be easily reduced and their strength further reduced by heat treatment.

Claims

1. A method for producing decomposition products of a decomposition resin composition, comprising the step of heating a decomposition resin composition containing a polyolefin resin, a cellulosic compound, and an organic acid metal salt at 40°C to 100°C, The cellulose-based compound is a cellulose nanofiber, and is present in an amount of 1 to 60 parts by mass per 100 parts by mass of the resin containing the polyolefin, and is dispersed in the resin containing the polyolefin. The aforementioned organic acid metal salt is present in an amount of 0.1 to 10 parts by mass per 100 parts by mass of the resin containing the polyolefin. A manufacturing method in which the weight-average molecular weight of polyolefins in the decomposition product is 100 g / mol to 10,000 g / mol.

2. The manufacturing method according to claim 1, wherein the polyolefin is selected from the group consisting of low-density polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene, chlorinated polyethylene, polytetrafluoroethylene, ethylene-α-olefin copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, polypropylene, chlorinated polypropylene, and polymethylpentene.

3. The manufacturing method according to claim 2, wherein the polyolefin is polypropylene or a propylene-ethylene copolymer.

4. The organic acid in the aforementioned organic acid metal salt is C ６ ~C ２２ aliphatic carboxylic acids and C ６ ~C ２２ The manufacturing method according to claim 1, selected from the group consisting of aromatic carboxylic acids.

5. The manufacturing method according to claim 4, wherein the carboxylic acid is a monocarboxylic acid.

6. The manufacturing method according to claim 1, wherein the metal of the organic acid metal salt is selected from the group consisting of aluminum, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, tin, lanthanum, cerium, tungsten, antimony, and bismuth.

7. The manufacturing method according to claim 1, comprising the step of kneading a biodegradable resin composition comprising a resin containing polyolefin, a cellulosic compound, and an organic acid metal salt to produce a molded article.

8. The manufacturing method according to claim 1, wherein the heating is performed for 1 week to 6 months.

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