Polyacetal resin composition

Abstract

The present invention provides a polyoxymethylene resin composition for use in mixing with metal powder, the polyoxymethylene resin composition containing 100 parts by weight of polyoxymethylene resin (A) and 0.15 to 10.0 parts by weight of fatty acid metal salt (B), the fatty acid metal salt (B) being zinc fatty acid, magnesium fatty acid, or a combination thereof.

Description

Technical Field

[0001] This invention relates to polyacetal resin compositions for use in compounding with metal powders. The invention also relates to methods for manufacturing polyacetal resin compositions, metal resin compositions containing polyacetal resin compositions and metal powders, and methods for manufacturing powder injection molded articles in which the polyacetal resin composition is used as an adhesive resin composition. Background Technology

[0002] In recent years, powder injection molding has been developed. This method involves mixing a binder resin composition with metal powder and then injection molding the resulting mixture to produce metal molded articles. Powder injection molding offers superior freedom in the shape and material of the molded articles, as well as dimensional accuracy.

[0003] Polyacetal resins are widely used as engineering plastics due to their mechanical properties, friction and wear characteristics, chemical resistance, heat resistance, and electrical properties. Polyacetal resins can be easily removed by combustion, and the amount of ash residue can be reduced, making them a preferred binder resin composition for metal powders in powder injection molding.

[0004] Patent Document 1 discloses an invention that provides a polyacetal resin composition with excellent extrudability, thermal stability, foreign matter suppression, and excellent dispersibility with metal powder, as well as a metal resin composition of a metal powder and polyacetal resin composition with excellent extrudability and thermal stability, low foreign matter content, and effective dispersion of metal powder. The polyacetal resin composition contains 100 parts by weight of (A) polyacetal resin, 0.005 to 0.2 parts by weight of (B) a nitrogen-containing compound, and 0.01 to 0.8 parts by weight of (C) a fatty acid metal salt. The melt flow index, measured at 190°C and 2.16 kg, is 60 g / 10 min or more and less than 200 g / 10 min. The ratio of the content of (C) the fatty acid metal salt to the content of (B) the nitrogen-containing compound ((C) / (B)) is 1 to 15.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2020-041133 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] When polyacetal resin compositions are used in compounding with metal powders (i.e., as a binder for metal powders), the compound (metal-resin composition) is required to have excellent properties in both flexural strain and flowability.

[0010] In view of this, the object of the present invention is to provide a polyacetal resin composition for use in compounding with metal powder. The present invention also provides a method for manufacturing a polyacetal resin composition, a metal resin composition comprising a polyacetal resin composition and metal powder, and a method for manufacturing a powder injection molded article in which the polyacetal resin composition is used as an adhesive resin composition.

[0011] Technical solutions for solving technical problems

[0012] The present invention includes the following methods [1] to [8].

[0013] [1] A polyacetal resin composition for use in compounding with metal powder, wherein the polyacetal resin composition contains 100 parts by weight of polyacetal resin (A) and 0.15 to 10.0 parts by weight of a fatty acid metal salt (B).

[0014] The aforementioned fatty acid metal salt (B) is zinc fatty acid, magnesium fatty acid, or a combination thereof.

[0015] [2] The polyacetal resin composition as described in [1], wherein the fatty acid of the fatty acid metal salt (B) is a fatty acid having 12 to 28 carbon atoms.

[0016] [3] The polyacetal resin composition as described in [1], wherein the fatty acid metal salt (B) is selected from at least one of magnesium laurate, zinc laurate, magnesium stearate, zinc stearate, magnesium benzyl laurate, zinc benzyl laurate, magnesium lignite, and zinc lignite.

[0017] [4] The polyacetal resin composition as described in any one of [1] to [3], wherein the polyacetal resin composition contains 1.0 to 10.0 parts by weight of the above-mentioned fatty acid metal salt (B).

[0018] [5] The polyacetal resin composition as described in any one of [1] to [4], wherein the melt flow rate of the polyacetal resin (A) is 40 to 100 g / 10 min (2.16 kg, 190 °C).

[0019] [6] A metal resin composition comprising the polyacetal resin composition described in any one of [1] to [5] and metal powder.

[0020] [7] A method for manufacturing a polyacetal resin composition, wherein the polyacetal resin composition is used for mixing with metal powder.

[0021] The above manufacturing method includes a step of melt-blending 100 parts by weight of polyacetal resin (A) and 0.15 to 10.0 parts by weight of fatty acid metal salt (B).

[0022] The aforementioned fatty acid metal salt (B) is zinc fatty acid, magnesium fatty acid, or a combination thereof.

[0023] [8] A method for manufacturing a powder injection molded article, comprising the step of injecting a mixture obtained by melt-mixing a metal powder and a binder resin composition into a mold.

[0024] The above-mentioned adhesive resin composition is any one of the polyacetal resin compositions described in [1] to [5].

[0025] Invention Effects

[0026] By using the polyacetal resin composition of the present invention to blend with metal powder, the blend (metal resin composition) has excellent properties in both flexural strain and flowability. Detailed Implementation

[0027] [Polyacetal resin composition]

[0028] The polyacetal resin composition of the present invention contains 100 parts by weight of polyacetal resin (A) and 0.15 to 10.0 parts by weight of a fatty acid metal salt (B), wherein the fatty acid metal salt (B) is zinc fatty acid, magnesium fatty acid, or a combination thereof. The polyacetal resin composition of the present invention is used in combination with metal powder (C) and serves as a binder resin composition for the metal powder (C). The polyacetal resin composition can be in solid, powder, strand, or granular form.

[0029] The method for manufacturing the polyacetal resin composition of the present invention includes a step of melt-blending 100 parts by weight of polyacetal resin (A) and 0.15 to 10.0 parts by weight of a fatty acid metal salt (B), wherein the fatty acid metal salt (B) is zinc fatty acid, magnesium fatty acid, or a combination thereof. The melt-blending step is carried out at a temperature above the melting temperature of the polyacetal resin composition (typically above 180°C).

[0030] [Polyacetal resin (A)]

[0031] Polyacetal resin (A) is a polymer whose repeating unit has an acetal bond: -O-CRH- (where R represents a hydrogen atom or an organic group), and usually uses the oxymethylene (-OCH2-) with R as a hydrogen atom as the main structural unit. Polyacetal resin (A) can also be a copolymer (block copolymer) or terpolymer containing more than one type of repeating structural unit other than oxymethylene. In addition, polyacetal resin (A) can not only have a linear structure, but also a branched, crosslinked structure generated by using glycidyl ether compounds, epoxy compounds, allyl ether compounds, etc. as comonomers and / or terpolymers. Other structural units besides oxymethylene can include, for example, branchable oxyalkylene groups with 2 to 10 carbon atoms, such as oxyethylene (-OCH2CH2- or -OCH(CH3)-), oxypropylene (-OCH2CH2CH2-, -OCH(CH3)CH2- or -OCH2CH(CH3)-), oxybutylene (-OCH2CH2CH2CH2-, -OCH(CH3)CH2CH2-, -OCH2CH(CH3)CH2-, -OCH2CH2CH(CH3)-, -OCH(C2H5)CH2- or -OCH2CH(C2H5)-). Among these, branchable oxyalkylene groups or oxyethylene (-OCH2CH2-) with 2 to 4 carbon atoms are preferred. In addition, based on the weight of polyacetal resin (A), the content of comonomers (structural units other than oxymethylene) in polyacetal resin (A) is 0.1 wt% to 20 wt%, 0.5 wt% to 20 wt%, 1.0 wt% to 20 wt%, 2.0 wt% to 20 wt%, 4.0 wt% to 20 wt%, 1.0 wt% to 15 wt%, 1.0 wt% to 10 wt%, 1.0 wt% to 10 wt%, 2.0 wt% to 15 wt%, 2.0 wt% to 10 wt%, 2.0 wt% to 8.0 wt%, 4.0 wt% to 10 wt%, or 4.0 wt%.

[0032] The polyacetal resin (A) can be either the end-stabilized resin or the unstabilized resin. That is, the end-stabilized polyacetal resin (A) can be melt-blended with a fatty acid metal salt (B) to prepare a polyacetal resin composition, or the unstabilized polyacetal resin (A) can be melt-blended with a fatty acid metal salt (B) to prepare a polyacetal resin composition.

[0033] The polyacetal resin (A) is preferably a copolymer of cyclic acetals such as trioxane or tetraoxane with ethylene oxide or 1,3-dioxolane. For example, the polyacetal resin (A) is an acetal copolymer using 1,3-dioxolane as a comonomer.

[0034] The polyacetal resin (A) has melt flow rates of 1–100 g / 10 min, 10–100 g / 10 min, 15–100 g / 10 min, 20–100 g / 10 min, 25–100 g / 10 min, 30–100 g / 10 min, 35–100 g / 10 min, 40–100 g / 10 min, 45–100 g / 10 min, or 45–95 g / 10 min, as measured according to ASTM-D1238 (conditions 190°C, load 2.16 kg). The polyacetal resin (A) preferably has melt flow rates of 30–100 g / 10 min, 40–100 g / 10 min, or 45–95 g / 10 min.

[0035] There is no particular limitation on the manufacturing method of polyacetal resin (A), and it can be manufactured using known methods. For example, polyacetal resin (A) with oxymethylene and oxyalkylene groups having 2 to 4 carbon atoms as structural units can be manufactured by copolymerizing cyclic acetals with oxymethylene groups, such as formaldehyde trimer (trioxane) or tetraoxane (tetraoxane), with cyclic acetals containing oxyalkylene groups having 2 to 5 carbon atoms, such as ethylene oxide, 1,3-dioxolane, 1,3,6-trioxane-octane, or 1,3-dioxane-heptane.

[0036] For example, polyacetal resin (A) can be obtained by integrally polymerizing a cyclic acetal containing an oxymethylene group and a cyclic acetal containing an oxyalkylene group as a comonomer using a polymerization catalyst. A reaction terminator can be used as needed to deactivate the polymerization catalyst and the polymer's growth ends. Furthermore, a molecular weight regulator can be used as needed to adjust the molecular weight of polyacetal resin (A).

[0037] There are no limitations on the types and amounts of polymerization catalysts, reaction terminators, and molecular weight regulators, as long as they do not impair the effects of the present invention. Well-known polymerization catalysts, reaction terminators, and molecular weight regulators can be used appropriately.

[0038] The polymerization catalyst may be, for example, Lewis acids such as boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentachloride, phosphorus pentafluoride, arsenic pentafluoride, and antimony pentafluoride, or coordination compounds or salts of these Lewis acids; protic acids such as trifluoromethanesulfonic acid or perchloric acid; esters of protic acids such as perchloric acid and lower aliphatic alcohols; protic anhydrides such as mixed anhydrides of perchloric acid and lower aliphatic carboxylic acids; or triethyloxonium hexafluorophosphate, triphenylmethyl hexafluoroarsenate, acetyl hexafluoroborate, heteropolyacids or their acidic salts, isopolyacids or their acidic salts, perfluoroalkyl sulfonic acids or their acidic salts.

[0039] Reaction terminators may be, for example, trivalent organophosphorus compounds, amine compounds, alkali metals, alkaline earth metal hydroxides, or combinations thereof. Molecular weight modifiers may be, for example, methyl acetal, methoxymethyl acetal, dimethoxymethyl acetal, trimethoxymethyl acetal, or oxymethylene di-n-butyl ether.

[0040] Furthermore, known additives such as antioxidants, heat stabilizers, colorants, nucleating agents, plasticizers, fluorescent whitening agents, lubricants, antistatic agents, ultraviolet absorbers, or light stabilizers can be added to the polyacetal resin (A) as needed.

[0041] [Fatty acid metal salt (B)]

[0042] The fatty acid metal salt (B) is zinc fatty acid, magnesium fatty acid, or a combination thereof. The fatty acid metal salt (B) is a salt of a fatty acid having 12 to 28 carbon atoms with zinc or magnesium. Examples of fatty acids having 12 to 28 carbon atoms include lauric acid, palmitic acid, stearic acid, benzyl acid, linoleic acid, 12-hydroxystearic acid, oleic acid, or erucic acid. Preferably, the zinc fatty acid is zinc stearate, zinc laurate, zinc benzyl acid, or zinc linoleate, and the magnesium fatty acid is magnesium laurate, magnesium stearate, magnesium benzyl acid, or magnesium linoleate.

[0043] The content of fatty acid metal salt (B) in the polyacetal resin composition is 0.15 to 10.0 parts by weight relative to 100 parts by weight of polyacetal resin (A). Specifically, the content of fatty acid metal salt (B) in the polyacetal resin composition can be 0.15 to 8.0 parts by weight, 0.15 to 6.0 parts by weight, 0.2 to 10.0 parts by weight, 0.2 to 8.0 parts by weight, 0.2 to 6.0 parts by weight, 0.3 to 10.0 parts by weight, 0.3 to 8.0 parts by weight, 0.3 to 6.0 parts by weight, 0.5 to 10.0 parts by weight, 0.5 to 8.0 parts by weight, 0.5 to 6.0 parts by weight, 1.0 to 10.0 parts by weight, 1.0 to 8.0 parts by weight, 1.0 to 6.0 parts by weight, 2.0 to 10.0 parts by weight, 2.0 to 8.0 parts by weight, or 2.0 to 6.0 parts by weight.

[0044] [Method for manufacturing polyacetal resin composition]

[0045] The method for manufacturing the polyacetal resin composition of the present invention includes a melt-blending step of melt-blending polyacetal resin (A) and a fatty acid metal salt (B). Melt-blending can be performed, for example, using a Bamberley mixer, rollers, a Brabender mixer, a single-screw extruder or a twin-screw extruder, or a kneader.

[0046] The temperature, pressure, and other conditions of the melt mixing process can be appropriately selected based on currently known methods for manufacturing polyacetal resin compositions. For example, the melt mixing process can be carried out above the melting temperature of the polyacetal resin, typically preferably at 180–240°C, and more preferably at 200–220°C.

[0047] The polyacetal resin (A) and fatty acid metal salt (B) can be melt-blended in one step to produce a polyacetal resin composition, with the final content of fatty acid metal salt (B) reaching the aforementioned level. Alternatively, the fatty acid metal salt (B) can be added separately in the same step. Alternatively, a polyacetal resin composition containing a high concentration of fatty acid metal salt (B) can be temporarily produced and then diluted by blending with other polyacetal resins.

[0048] The fatty acid metal salt (B) contained in the polyacetal resin composition is zinc fatty acid, magnesium fatty acid, or a combination thereof. The content of fatty acid metal salt (B) is 0.15 to 10.0 parts by weight relative to 100 parts by weight of polyacetal resin (A), so that the compound of polyacetal resin composition and metal powder (C) (metal resin composition) can have excellent properties in both flexural strain and flowability.

[0049] [Metal-resin composition]

[0050] The metal resin composition of the present invention comprises the above-described polyacetal resin composition and metal powder (C). The metal resin composition is manufactured by melt-blending the above-described polyacetal resin composition with metal powder (C). The melt-blending process is performed at a temperature above the melting point of the polyacetal resin composition (typically 180°C or higher). The metal resin composition (blended body) can be in solid, powder, strand, or granular form.

[0051] The metal resin composition exhibits excellent properties in both flexural strain and flowability. Regarding flexural strain (%), a three-point bending test was performed on a molded sheet of the metal resin composition using an apparatus such as the "Autograph (registered trademark) AGS-X" manufactured by Shimadzu Corporation at a bending speed of 2 mm / min, with the point of highest flexural strength being used for measurement. Regarding flowability (g / 10 min), measurements were performed based on ASTM-D1238 at a temperature of 190°C and a load of 10 kg. The metal resin composition exhibits a flexural strain of 1.0% or more and a flowability of 10 g / 10 min or more. Furthermore, the metal resin composition exhibits flexural strains of 1.0–15%, 1.0–12%, 1.0–10%, 1.0–9.5%, or 1.1–9.1%, and flowability of 11–2000 g / 10 min, 11–1800 g / 10 min, or 11–1700 g / 10 min.

[0052] [Metal powder (C)]

[0053] The metal powder (C) is made of iron, aluminum, magnesium, cobalt, zinc, copper, nickel, titanium, tungsten, or a metal compound or alloy based thereon. Preferably, the metal powder (C) is stainless steel (SUS) powder, specifically austenitic stainless steel (SUS300 series), ferritic and martensitic stainless steel (SUS400 series), or precipitation-hardening stainless steel (SUS600 series). The particle size (average particle size) of the metal powder (C) is determined using electron microscopy or laser diffraction / scattering particle size distribution measurement, and can be 1–100 μm, 1–50 μm, 1–25 μm, or 1–10 μm, but is not particularly limited.

[0054] Based on the weight of the metal resin composition, the content of metal powder (C) in the metal resin composition is 60-95% by weight, 65-95% by weight, 70-95% by weight, 80-95% by weight, or 85-95% by weight.

[0055] [Manufacturing method of powder injection molded articles]

[0056] The method for manufacturing a powder injection molded article of the present invention includes a step of injecting a compound obtained by melt-blending a metal powder (C) and a binder resin composition into a mold, wherein the binder resin composition is the aforementioned polyacetal resin composition. Additionally, the manufacturing method may include a step of removing the binder resin composition from the molded compound by heating or by using a gaseous acid in a degreasing furnace; and a step of sintering the molded compound in a sintering furnace to form a powder injection molded article.

[0057] [Any ingredient]

[0058] In the polyacetal resin composition, without prejudice to the purpose of this invention, other additives such as stabilizers, nucleating agents, release agents, fillers, pigments, lubricants, plasticizers, ultraviolet absorbers, flame retardants, or flame retardant auxiliaries may be added as needed. Examples of such additives include glass fiber, glass sheets, glass beads, wollastonite, mica, talc, boron nitride, calcium carbonate, kaolin, silica, clay, asbestos, silica, diatomaceous earth, graphite, molybdenum disulfide, glass fiber, middle fiber, potassium titanate fiber, boron fiber, carbon fiber, aramid fiber, potassium titanate whiskers, carbon black, or pigments.

[0059] Example

[0060] Hereinafter, an embodiment of the present invention will be described. The materials used in the embodiment and comparative examples are as follows.

[0061] [Polyacetal resin (A)]

[0062] As the polyacetal resin (A-1), the polyacetal resin "Iupital (registered trademark) F40-05" manufactured by Mitsubishi Engineering Plastics Co., Ltd. was used. The melt flow rate of the polyacetal resin (A-1) was 47 g / 10 min (measured according to ASTM-D1238, at a load of 2.16 kg and 190 °C).

[0063] As the polyacetal resin (A-2), the polyacetal resin "Iupital (registered trademark) F50-05" manufactured by Mitsubishi Engineering Plastics Co., Ltd. was used. The melt flow rate of the polyacetal resin (A-2) was 90 g / 10 min (measured according to ASTM-D1238, at a load of 2.16 kg and 190 °C).

[0064] [Fatty acid metal salt (B)]

[0065] The fatty acid metal salt (B-1) is magnesium stearate "MAGNESIUM STEARATE" manufactured by Nippon Oil Co., Ltd.

[0066] The fatty acid metal salt (B-2) is zinc stearate "ZINC STEARATE" manufactured by Nippon Oil Co., Ltd.

[0067] The fatty acid metal salt (B-3) is zinc laurate "ZS-3" manufactured by Nitto Kasei Corporation.

[0068] The fatty acid metal salt (B-4) is zinc betaine "ZS-7" manufactured by Nitto Kasei Corporation.

[0069] The fatty acid metal salt (B-5) is zinc lignite "ZS-8" manufactured by Nitto Kasei Corporation.

[0070] The fatty acid metal salt (B-6) is calcium stearate manufactured by Nippon Oil Co., Ltd.

[0071] [Metal powder (C)]

[0072] The metal powder (C) is SUS630 powder (average particle size approximately 10 μm) manufactured by Epson Atmix Corporation.

[0073] [Example 1]

[0074] As shown in Table 1, 0.15 parts by weight of magnesium stearate (B-1) were added to 100 parts by weight of polyacetal resin (A-1), and the mixture was melt-mixed for 20 minutes under a nitrogen flow at a set temperature of 220°C and a rotation speed of 30 rpm using a "LABO PLASTOMILL (registered trademark) 4C150" mixer manufactured by Toyo Seiki Co., Ltd., thereby preparing the polyacetal resin composition of Example 1. For 20 g of this polyacetal resin composition (10% by weight based on the weight of the mixture) and 180 g of metal powder (C) (90% by weight based on the weight of the mixture), the mixture was mixed for 40 minutes under a nitrogen flow at a set temperature of 180°C and a rotation speed of 60 rpm, and then cooled and solidified to prepare a mixture (metal resin composition). The mixture was crushed using a Granutter (registered trademark) SPC-400 pelletizer manufactured by HARMOCo., Ltd.

[0075] [Examples 2-47]

[0076] Similar to Example 1, the polyacetal resin (A) and fatty acid metal salt (B) were melt-blended according to the types and proportions (parts by weight) of polyacetal resin (A) and fatty acid metal salt (B) shown in Tables 1 to 3, thereby preparing the polyacetal resin compositions of Examples 2 to 47.

[0077] Similar to Example 1, in Examples 2-41, 20g (10 wt%) of the polyacetal resin composition and 180g (90 wt%) of metal powder (C) were mixed in the above-mentioned mixer at a set temperature of 180°C, a rotation speed of 60 rpm, and a nitrogen flow for 40 minutes, and then cooled and solidified to prepare a compound (metal-resin composition). In Examples 42-47, 60g (30 wt%) of the polyacetal resin composition and 140g (70 wt%) of metal powder (C) were mixed in the above-mentioned mixer at a set temperature of 180°C, a rotation speed of 60 rpm, and a nitrogen flow for 40 minutes, and then cooled and solidified to prepare a compound (metal-resin composition). The compounds of Examples 2-47 were then crushed using the above-mentioned pelletizer.

[0078] [Comparative Examples 1-12]

[0079] Similar to the examples, the polyacetal resin compositions of Comparative Examples 1-12 were prepared by melt-blending only polyacetal resin (A) (Comparative Examples 1-2) or by melt-blending polyacetal resin (A) and fatty acid metal salt (B) (Comparative Examples 3-12) according to the types and proportions (parts by weight) of polyacetal resin (A) and fatty acid metal salt (B) shown in Table 4. Similar to the examples, melt-blending was performed using a "LABO PLASTOMILL (registered trademark) 4C150" mixer manufactured by Toyo Seiki Co., Ltd., at a set temperature of 220°C, a rotation speed of 30 rpm, and under a nitrogen flow for 20 minutes. In Comparative Examples 1-12, 20 g (10% by weight) of the polyacetal resin composition and 180 g (90% by weight) of metal powder (C) were respectively blended using the above-mentioned mixer at a set temperature of 180°C, a rotation speed of 60 rpm, and under a nitrogen flow for 40 minutes, followed by cooling and solidification to produce a compound (metal-resin composition). These mixtures were crushed using the aforementioned particle breaker. Comparative Example 11 was prepared according to the composition of Example 5 of Patent Document 1.

[0080] The bending strain and flowability of the mixtures (metal-resin compositions) of Examples 1-47 and Comparative Examples 1-12 were evaluated as follows.

[0081] [Measurement and Evaluation Methods]

[0082] (1) Bending strain

[0083] Using the crushed mixture, a 12.7mm × 63.5mm × 3.2mm thick molded sheet was produced using a Thermo Fisher Scientific "HAAKE MiniJet" benchtop injection molding machine at a barrel temperature of 220°C. A three-point bending test was performed on the molded sheet using an "Autograph (registered trademark) AGS-X" machine manufactured by Shimadzu Corporation at a bending speed of 2mm / min, and the point with the highest bending strength was taken as the bending strain (%). In this invention, a bending strain (%) value of 1.0 (%) or higher is considered acceptable, indicating excellent bending strain characteristics.

[0084] (2) Liquidity

[0085] Using a melt flow indexer "L241" manufactured by Takara Industrial Co., Ltd., the flowability of the crushed compound was measured according to ASTM-D1238 at a temperature of 190°C and a load of 10 kg. In this invention, a flowability (g / 10 min) value of 10 (g / 10 min) or higher is evaluated as acceptable, indicating excellent flowability characteristics.

[0086]

[0087]

[0088] [Table 3]

[0089]

[0090]

[0091] As shown in Tables 1-3, the polyacetal resin compositions and metal powder mixtures (metal-resin compositions) of Examples 1-47 exhibit both flexural strain of 1.0% or more and flowability of 10 g / 10 minutes or more. Furthermore, as shown in Table 4, the polyacetal resin compositions and metal powder mixtures (metal-resin compositions) of Comparative Examples 1-12 do not exhibit either or one of the characteristics of flexural strain of 1.0% or more and flowability of 10 g / 10 minutes or more, which is worse than the case using the polyacetal resin compositions of Examples 1-47.

Claims

1. A metal resin composition, characterized in that: Contains a polyacetal resin composition and metal powder. The polyacetal resin composition contains 100 parts by weight of polyacetal resin (A) and 1.0 to 10.0 parts by weight of fatty acid metal salt (B). The fatty acid metal salt (B) is zinc fatty acid, magnesium fatty acid, or a combination thereof, wherein the fatty acid of the fatty acid metal salt (B) is a fatty acid having 12 to 28 carbon atoms. The metal powder is made of iron or an iron-based metal alloy. Based on the weight of the metal resin composition, the content of the metal powder in the metal resin composition is 60-95% by weight.

2. The metal resin composition according to claim 1, characterized in that: The fatty acid metal salt (B) is selected from at least one of magnesium laurate, zinc laurate, magnesium stearate, zinc stearate, magnesium benzene, zinc benzene, magnesium lignite, and zinc lignite.

3. The metal resin composition according to claim 1 or 2, characterized in that: The melt flow rate of the polyacetal resin (A) at 2.16 kg and 190 °C is 40-100 g / 10 min.

4. A method for manufacturing a metal resin composition, characterized in that, include: The process of manufacturing a polyacetal resin composition by melt-blending 100 parts by weight of polyacetal resin (A) and 1.0 to 10.0 parts by weight of fatty acid metal salt (B); and The process of melt-blending the polyacetal resin composition with metal powder. The fatty acid metal salt (B) is zinc fatty acid, magnesium fatty acid, or a combination thereof, wherein the fatty acid of the fatty acid metal salt (B) is a fatty acid having 12 to 28 carbon atoms. The metal powder is made of iron or an iron-based metal alloy. Based on the weight of the metal resin composition, the content of the metal powder in the metal resin composition is 60-95% by weight.

5. A method for manufacturing a powder injection molded article, characterized in that: This includes the process of injecting a metal-resin composition, obtained by melt-mixing metal powder with a binder resin composition, into a mold. The metal resin composition is any one of the metal resin compositions according to claims 1 to 3.

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