TW202016208A - Polyoxymethylene resin composition and metal resin composition containing polyoxymethylene resin, nitrogen-containing compound and fatty acid metal salt - Google Patents

Abstract

An object of the present invention is to provide a polyoxymethylene resin composition excellent in extrudability, thermal stability, and suppression of foreign matter, and further excellent in dispersibility with metal powder, and a metal resin composition which is excellent in extrudability and thermal stability, contains less foreign matter, and further effectively disperses metal powder and polyoxymethylene resin composition. The polyoxymethylene resin composition of the present invention comprises (A) 100 parts by mass of polyoxymethylene resin, (B) 0.005 to 0.2 parts by mass of nitrogen-containing compound, and (C) 0.01 to 0.8 parts by mass of fatty acid metal salt. The melt flow index measured under the conditions of 190 DEG C and 2.16 kg is 60 g/10 minutes or more and less than 200 g/10 minutes. The ratio of the content of (C) fatty acid metal salt to the content of (B) nitrogen-containing compound ((C) / (B)) is 1 to 15. Moreover, the metal resin composition of this invention is a metal resin composition containing a metal powder and the said polyoxymethylene resin composition, and the content of this metal powder is 70 to 95 mass% in 100 mass% of the metal resin composition.

Description

Polyacetal resin composition and metal resin composition

The present invention relates to a polyacetal resin composition and a metal resin composition.

Polyacetal resin compositions are widely used in parts of automobiles, electronic equipment, electrical equipment, etc. due to their balanced mechanical properties and excellent fatigue properties. However, in recent years, the use of polyacetal resin compositions as adhesives for metal powder injection molding has also increased. As a technique for using polyacetal resins as adhesives, for example, it is introduced that the adhesive component contains polyacetal Technology of resin, polyolefin resin and other polymers (Patent Document 1). [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Special Publication No. 2017-530029 [Patent Document 2] Japanese Patent Laid-Open No. 2011-32379

[Problems to be solved by the invention]

Here, as the characteristics required for the polyacetal resin composition used as a binder for injection molding of metal powder, the fluidity is high because the metal powder is uniformly dispersed in the polyacetal resin composition (High melt flow index (MI)); excellent thermal stability from the viewpoint of the operating environment; and in order to suppress the effect on the final metal product, due to poor thermal stability or extrudability, etc. The content of foreign substances such as formaldehyde or carbides of additives is low. As a technique for improving thermal stability, for example, a technique for blending two kinds of antioxidants, fatty acid calcium salts, formaldehyde-reactive nitrogen-containing compounds and lubricants in polyacetal resin to improve heat resistance, solvent resistance and acid resistance (Patent Literature 2)

However, in the techniques described in Patent Documents 1 and 2, the characteristics required for the above-mentioned polyacetal resin composition are not sufficient. Especially in Patent Document 2, the physical properties of the polyacetal resin composition with a relatively high MI There is room for improvement.

The object of the present invention is to provide a polyacetal resin composition which is excellent in extrudability, thermal stability, and suppression of foreign matter and excellent in dispersibility with metal powder, and which is excellent in extrudability and thermal stability, and contains less foreign matter. Furthermore, the metal powder in which the metal powder is effectively dispersed and the metal resin composition of the polyacetal resin composition. [Technical means to solve the problem]

The inventors of the present invention have made intensive studies to solve the above problems and found that the polyacetal resin contains a nitrogen-containing compound and a fatty acid metal salt at a specific content, and the content of the nitrogen-containing compound and fatty acid metal salt is specified Ratio to produce a polyacetal resin composition with a specific melt flow index, thereby solving the above-mentioned problems and completing the present invention.

That is, the present invention is as follows. [1] A polyacetal resin composition, characterized in that it comprises (A) 100 parts by mass of polyacetal resin, (B) 0.005 to 0.2 parts by mass of nitrogen-containing compound and (C) 0.01 to 0.8 parts by mass of fatty acid metal salt, And the melt flow index measured under the conditions of 190°C and 2.16 kg is 60 g/10 minutes or more and less than 200 g/10 minutes, The ratio ((C)/(B)) of the content of the (C) fatty acid metal salt to the content of the (B) nitrogen-containing compound is 1 to 15. [2] The polyacetal resin composition as described in [1], wherein the ratio of the content of the (C) fatty acid metal salt to the content of the (B) nitrogen-containing compound ((C)/(B)) is 1 to 10 . [3] The polyacetal resin composition as described in [1] or [2], which is relative to 100 parts by mass of the (A) polyacetal resin, The content of the (B) nitrogen-containing compound is 0.005 to 0.1 parts by mass, and the content of the (C) fatty acid metal salt is 0.01 to 0.6 parts by mass. [4] The polyacetal resin composition as described in any one of [1] to [3], which further contains (D) in a content of 0.01 to 1.0 parts by mass relative to 100 parts by mass of the (A) polyacetal resin. Antioxidants. [5] A metal resin composition comprising a metal powder and the above polyacetal resin composition as described in any one of [1] to [4], the content of the metal powder being 100% by mass of the metal resin composition 70 to 95% by mass. [Effect of invention]

According to the present invention, it is possible to provide a polyacetal resin composition excellent in extrudability, thermal stability, and suppression of foreign matter and excellent in dispersibility with metal powder, and a metal resin composition of metal powder and polyacetal resin composition .

The form for implementing the present invention will be described in detail below. In addition, the present invention is not limited to the following description, and can be implemented with various changes within the scope of the gist thereof.

(Polyacetal resin composition) The polyacetal resin composition of this embodiment includes (A) 100 parts by mass of polyacetal resin, (B) 0.005 to 0.2 parts by mass of nitrogen-containing compound, and (C) 0.01 to 0.8 parts by mass of fatty acid metal salt. In addition, the resin composition is characterized in that the melt flow index measured under the conditions of 190°C and 2.16 kg is 60 g/10 minutes or more and less than 200 g/10 minutes. (C) The content of the fatty acid metal salt relative to (B) The content ratio of the nitrogen-containing compound ((C)/(B)) is 1 to 15. Thereby, the extrusion property, thermal stability, and suppression of foreign matter when manufacturing the polyacetal resin composition can be excellent, and the dispersibility with the metal powder can also be excellent.

[(A) Polyacetal resin] The (A) polyacetal resin in this embodiment is a polyacetal homopolymer, a polyacetal copolymer, or a mixture thereof. From the viewpoint of thermal stability, the (A) polyacetal resin in the present embodiment is preferably a polyacetal copolymer. The polyacetal homopolymer is a polymer with a formaldehyde group in the main chain, and the two ends of the polymer can be blocked by an ester group or an ether group. The polyacetal homopolymer can be obtained by using formaldehyde and a known molecular weight regulator as raw materials. Based on these raw materials, a well-known onium salt-based polymerization catalyst can be used, and a hydrocarbon or the like can be used as a solvent. It is obtained by the polymerization method described in Japanese Patent Publication No. 47-6420 or Japanese Patent Publication No. 47-10059. Furthermore, the polyacetal homopolymer is preferably a polyacetal homopolymer containing more than 99.8 mol% of the main chain except for two end caps, which contains formaldehyde groups, and more preferably the main chain except for two end caps contains only formaldehyde Based polyacetal homopolymer.

The polyacetal copolymer is a polyacetal resin obtained by copolymerizing trioxane with cyclic ether and/or cyclic methylal in the presence of a polymerization catalyst. Tricyclohexane-based formaldehyde cyclic trimer is generally obtained by reacting an aqueous formalin solution in the presence of an acid catalyst. Since the trioxane contains impurities that cause chain transfer of water, methanol, formic acid, methyl formate, etc., it is preferable to remove and purify these impurities by a method such as distillation. In this case, the total amount of impurities for chain transfer is preferably 1×10 ⁻³ mol or less, and more preferably 0.5×10 ⁻³ mol or less, relative to 1 mol of trioxane. By reducing the amount of impurities as described above, it is possible to sufficiently increase the polymerization reaction rate practically and obtain excellent thermal stability in the resulting polymer.

The cyclic ether and/or cyclic methylal is a component that can be copolymerized with the above-mentioned trioxane, and examples include ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, and bromopropylene oxide , Oxirane, oxetane, 1,3-dioxolane, ethylene glycol methylal, propylene glycol methylal, diethylene glycol methylal, triethylene glycol methylal, 1,4-butanediol methylal, 1,5-pentanediol methylal, 1,6-hexanediol methylal, etc. Particularly preferred are 1,3-dioxolane and 1,4-butanediol methylal. These may be used alone or in combination of two or more.

The added amount of cyclic ether and cyclic methylal is preferably 1.0 mol% or more, more preferably 3.0 mol% or more, and still more preferably 3.5 mol% or more relative to 1 mol of the above triethane. In addition, it is preferably 8.0 mol% or less, more preferably 7.0 mol% or less, and further preferably 5.0 mol% or less with respect to 1 mol of the triethylene.

Examples of polymerization catalysts include polymerization catalysts represented by Lewis acids. Examples of Lewis acids include boron, tin, titanium, phosphorus, arsenic, and antimony halides. Particularly preferred are boron trifluoride and trifluoride. The coordination complex of boron hydrate and organic compound containing oxygen atom or sulfur atom and boron trifluoride. For example, preferred examples include boron trifluoride, boron trifluoride diethyl ether, and boron trifluoride di-n-butyl ether. These may be used alone or in combination of two or more.

The addition amount of the polymerization catalyst is preferably in the range of 0.1×10 ^-5 to 0.1×10 ^-3 mol, more preferably in the range of 0.3×10 ^-5 to 0.5×10 ^-4 mol, relative to 1 mol of the above-mentioned triethylene. It is further preferably in the range of 0.5×10 ^-5 to 0.4×10 ^-4 mol. When the addition amount of the polymerization catalyst is within the above range, the polymerization reaction for a long time can be stably carried out.

In the production of polyacetal copolymers, as for the deactivation of the polymerization catalyst, the polyacetal resin obtained by the polymerization reaction is charged with at least ammonia, triethylamine, tri-n-butylamine and other amines or alkali metals Or alkaline earth metal hydroxides, inorganic acid salts, organic acid salts and other catalysts neutralize at least one of the aqueous solution or organic solvent of the deactivator, generally stirring in the slurry state for several minutes to several hours, borrow Proceed. The catalyst-neutralized slurry is filtered and washed to remove unreacted monomer or catalyst-neutralized deactivator and catalyst-neutralized salt, and then dried.

In addition, as the deactivation of the polymerization catalyst, a method of deactivating the polymerization catalyst by contacting vapors of ammonia, triethylamine, etc. with the polyacetal copolymer, or inactivating hindered amines, triphenylphosphine, and At least one of calcium hydroxide and the like is in contact with the polyacetal resin in a mixer to inactivate the catalyst.

In addition, without deactivation of the polymerization catalyst, the polyacetal copolymer can be heated at a temperature below the melting point of the polyacetal copolymer and under an inert gas atmosphere. The following terminal stabilization treatment of the embodiment. The above deactivation operation of the polymerization catalyst and the reduction operation of the volatilization of the polymerization catalyst may be performed after pulverizing the polyacetal resin obtained by the polymerization reaction, if necessary.

The terminal stabilization treatment of the obtained (A) polyacetal resin is decomposed to remove unstable terminal parts by the following method. As a method for decomposing and removing unstable ends, for example, a single-screw extruder with a vent or a twin-screw extruder with a vent can be used, and ammonia, triethylamine, or tributyl as a cutting agent Aliphatic amines such as amines, hydroxides of alkali metals or alkaline earth metals represented by calcium hydroxide, inorganic weak acid salts, organic weak acid salts, etc. are known to decompose the unstable terminal part of the alkaline substance in the presence of The acetal resin melts and decomposes to remove unstable ends.

The melt flow index (MI) of the (A) polyacetal resin of this embodiment is measured according to ASTM-D-1238-57T under the conditions of 190°C and 2.16 kg, preferably 60 g/10 minutes or more and less than 200 g/10 minutes, more preferably 60 g/10 minutes or more and less than 160 g/10 minutes, and still more preferably 70 g/10 minutes or more and less than 140 g/10 minutes. By setting the melt flow index to 60 g/10 min or more, the dispersibility with the metal powder is improved, and by setting the melt flow index to less than 200 g/10 min, the dispersibility with the metal powder can be made It is improved and the extrudability when (A) polyacetal resin is extruded is also improved. Furthermore, (A) the melt flow index of the polyacetal resin can be manipulated in this way by increasing the amount of molecular weight modifier added during polymerization to make the melt flow index larger.

[(B) Nitrogen compounds] The polyacetal resin composition of this embodiment contains (B) a nitrogen-containing compound, which can be combined with (C) a fatty acid metal salt to improve thermal stability. The (B) nitrogen-containing compound is not particularly limited, and examples thereof include polyamide resins, amide compounds, urea derivatives, triamide derivatives, and the like. One of these may be used alone, or two or more may be used in combination. The polyamide resin is not particularly limited, and examples include: condensation of diamine and dicarboxylic acid, condensation of amino acid, nylon 6, nylon 11, and nylon obtained by ring-opening polymerization of internal amide. 12, Nylon 66, Nylon 6, 10, Nylon 6/6, 10, Nylon 6/6, 6, Nylon 6, 6/6, 10, Nylon 6/6, 6/6, 10, Poly-β-alanine Wait.

The amide compound is not particularly limited, and examples thereof include aliphatic monocarboxylic acid, aliphatic dicarboxylic acid, aromatic monocarboxylic acid or aromatic dicarboxylic acid and aliphatic monoamine, aliphatic diamine, aromatic Stearyl-based stearyl amine produced from aromatic monoamines and aromatic diamines, stearyl-based oleamide, stearyl erucamide, ethylenediamine-distearylamide, ethylenediamine-dishanconamide Amine, hexamethylenediamine-distearylamide, ethylenediamine-dieramide, xylylenediamine-dieramide, dixylylenediamine-stearylamide, sebacamide Amines.

The urea derivative is not particularly limited, and examples thereof include N-phenylurea, N,N′-diphenylurea, N-phenylthiourea, and N,N′-diphenylthiourea.

The tris derivatives are not particularly limited, and examples include melamine, benzoguanamine, N-phenyl melamine, melem, N,N'-diphenyl melamine, N-methylol melamine, N , N'-trimethylolmelamine, 2,4-diamino-6-cyclohexyl triamine, melam, etc.

The content of the (B) nitrogen-containing compound is 0.005 to 0.2 parts by mass, preferably 0.005 to 0.1 parts by mass relative to 100 parts by mass of the polyacetal resin. By setting the content to 0.005 parts by mass or more, the thermal stability can be improved, and the content of foreign matter can be suppressed. In addition, by setting the content to 0.2 parts by mass or less, the content of foreign matter can be suppressed.

[(C) fatty acid metal salt] The polyacetal resin composition of this embodiment contains (C) a fatty acid metal salt, which can be combined with (B) a nitrogen-containing compound to maintain long-term thermal stability. The (C) fatty acid metal salt is not particularly limited, and examples thereof include saturated or unsaturated fatty acids having a carbon number of 10 to 35 or fatty acids substituted with hydroxyl groups, and hydroxides, oxides or alkali metal or alkaline earth metal Metal salts of fatty acids obtained from chlorides.

Examples of fatty acids of fatty acid metal salts include capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadeic acid, arachidic acid, Behenic acid, tetracosanoic acid, oleic acid, dicetic acid, montanic acid, undecylenic acid, oleic acid, elaidic acid, cetenoic acid, erucic acid, brasenoic acid, hexadienoic acid, linoleic acid , Linolenic acid, arachidonic acid, propionic acid, stearic acid, 12-hydroxydodecanoic acid, 3-hydroxydecanoic acid, 16-hydroxyhexadecanoic acid, 10-hydroxyhexadecanoic acid, 12-hydroxyoctadecanoic acid Acid, 10-hydroxy-8-octadecanoic acid, etc. In addition, as the metal compound, sodium, lithium, potassium and calcium, magnesium, barium, zinc, aluminum, strontium alkali metal, alkaline earth metal hydroxide or chloride. Among them, fatty acids are myristic acid, palmitic acid, and stearic acid, and metal compounds are calcium hydroxide, oxide, and chloride. Examples of specific fatty acid metal salts include calcium myristate, calcium palmitate, and calcium stearate.

The content of the (C) fatty acid metal salt is 0.01 to 0.8 parts by mass, preferably 0.01 to 0.6 parts by mass relative to 100 parts by mass of the polyacetal resin. By setting the content to 0.01 parts by mass or more, the thermal stability can be improved, and the content of foreign matter can be suppressed. In addition, by setting the content to 0.8 parts by mass or less, the thermal stability can be improved, and the content of foreign matter can be suppressed.

[Ratio of (C) content of fatty acid metal salt relative to (B) content of nitrogen-containing compounds] In this embodiment, it is important that the ratio of the content of (C) fatty acid metal salt to the content of (B) nitrogen-containing compound is in a specific range, specifically, the ratio is 1 to 15, preferably 1 to 10. . By setting the ratio to 1 or more, the content of foreign matter can be suppressed. In addition, by setting the ratio to 15 or less, the thermal stability can be improved, and the content of foreign matter can be suppressed.

[Other additives] In this embodiment, other additives that can be added to the polyacetal resin composition are not particularly limited as long as the effects of the present invention are not impaired, and preferred additives include antioxidants. Examples of antioxidants include n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate and n-octadecyl-3-(3 '-Methyl-5'-tert-butyl-4'-hydroxyphenyl) propionate, n-tetradecyl-3-(3',5'-ditert-butyl-4'-hydroxybenzene Group) propionate, 1,6-hexanediol-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), 1,4-butanediol-bis( 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate), 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, triethylene glycol -Bis(3-(3-tertiarybutyl-5-methyl-4-hydroxyphenyl)propionate), tetrakis(methylene 3-(3,5-ditertiarybutyl-4-hydroxy Phenyl) propionate) methane, N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hydrazine, N,N'-tetramethylene -Bis 3-(3'-methyl-5'-tert-butyl-4-hydroxyphenyl)propanediamine, N,N'-bis 3-(3',5'-di-tert-butyl 4-hydroxyphenyl)propionylhexamethylenediamine, 3-(N-o-hydroxybenzyl)amino-1,2,4-triazole, N,N'-bis(2 -(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy)ethyl) oxamide, N,N'-hexamethylene-bis(3-(3, 5-di-tert-butyl-4-hydroxyphenyl) propylamide) etc. One type of these antioxidants may be used, or two or more types may be used in combination.

The content of the antioxidant is 0.01 to 1.0 part by mass, preferably 0.05 to 0.5 part by mass relative to 100 parts by mass of the polyacetal resin. When the content is within the above range, the thermal stability is improved.

[Characteristics of polyacetal resin composition] The melt flow index (MI) of the polyacetal resin composition of this embodiment is measured according to ASTM-D-1238-57T under the conditions of 190°C and 2.16 kg, and is 60 g/10 minutes or more and less than 200 g /10 minutes, preferably 60 g/10 minutes or more and less than 160 g/10 minutes, more preferably 70 g/10 minutes or more and less than 140 g/10 minutes. By setting the melt flow index to 60 g/10 minutes or more, the dispersibility with the metal powder is improved, and by setting the melt flow index to less than 200 g/10 minutes, the extrudability and heat stability Sex, foreign matter suppression, and improved dispersion with metal powder. Furthermore, the melt flow index of the polyacetal resin composition can be controlled to the above range by using the (A) polyacetal resin, for example, (A) the greater the melt flow index of the polyacetal resin, the polycondensation The melt flow index of the aldehyde resin composition also tends to increase.

[Manufacturing method of polyacetal resin composition] In this embodiment, the method for producing the polyacetal resin composition is not particularly limited, and can be produced by a known method. Specifically, by mixing the above components (A) to (C) and any additives equal to, for example, a Henschel mixer, a drum, a V-shaped stirrer, etc., a single-screw extruder or a double Shaft extruders, heating rollers, kneaders, Banbury mixers and other mixers are melt-kneaded and manufactured, and can be obtained as products in various forms such as linear and granular forms.

(Metal resin composition) The metal resin composition of this embodiment is a metal resin composition containing a metal powder and the polyacetal resin composition, and the content of the metal powder is 70 to 95% by mass in 100% by mass of the metal resin composition. By this, the extrudability, thermal stability, and suppression of foreign matter can be excellent, and the dispersibility with the metal powder can also be excellent. Furthermore, the metal resin composition can be used for metal powder injection molding. The metal powder is preferably metal or ceramic in order to impart functionality. Specific metals include aluminum, magnesium, barium, calcium, cobalt, zinc, copper, nickel, iron, silicon, titanium, tungsten, and metal compounds and metal alloys based on these. Here, not only the completed alloy but also a mixture of alloy components can be used.

As specific ceramics, oxides such as zinc oxide, aluminum oxide, and zirconium oxide; hydroxides such as hydroxide apatite; carbides such as silicon carbide; nitrides such as silicon nitride or boron nitride; fluorite Such as halides; silicates such as steatite; titanates such as barium titanate or lead zirconate; carbonates; phosphates; ferrite; high-temperature superconducting substances, etc. These inorganic substances may be used alone, or various inorganic substances such as various metals or metal alloys or ceramics may be used in combination. Examples of particularly preferable metals or alloys include titanium alloys and SUS316L, and examples of ceramics include Al ₂ O ₃ and ZrO ₂ . The particle size of these metals is preferably 30 μm or less, and more preferably 20 μm or less.

In this embodiment, the content of the metal powder in the metal resin composition containing the metal powder and the polyacetal resin composition is 70 to 95% by mass, preferably 80 to 90% by mass. The metal resin composition may optionally contain additives other than the metal powder and the polyacetal resin composition, but the content of the additive is preferably 5 mass% or less in 100 mass% of the metal resin composition, more preferably 2 mass % Or less, further preferably 0% by mass.

In this embodiment, the dispersibility of the metal powder in the metal resin composition is measured by the evaluation method described in the following examples, preferably 1.20 or less, more preferably 1.15 or less, and still more preferably 1.10 or less. By this, a molded body that is better than the metal resin composition is obtained.

[Manufacturing method of metal resin composition] In this embodiment, the method for producing the metal resin composition is not particularly limited, and can be produced by a known method. Specifically, a single-screw extruder or a twin-screw can be used after mixing the above-mentioned metal powder with a polyacetal resin composition, etc., for example, in a Henschel mixer, a drum, a V-shaped stirrer, etc. Mixers such as extruders, heated rolls, kneaders, and Banbury mixers are manufactured by melt-kneading in a semi-molten state, and can be obtained as products in various forms such as linear and granular forms. [Example]

The present invention will be described in detail below by giving specific examples and comparative examples, but the present invention is not limited to the following examples. In addition, the terms and measurement methods of the examples and comparative examples are as follows.

[(A) Polyacetal resin] (A-1) A double shaft paddle type continuous polymerization reactor (manufactured by Kurimoto Iron Works Co., Ltd., diameter 2B, L/D=14.8) which can be passed through a heat medium with a bushing is adjusted to a temperature of 80°C. Diluted boron trifluoride-di-n-butyl ether as the polymerization catalyst to 0.26% by mass of cyclohexane using a catalyst mixture of 69 g/hr, triethylene 3500 g/hr, and 1,3-dioxane 121 g/hr of pentane and 7.1 g/hr of methylal as a molecular weight regulator were continuously supplied to the polymerization reactor for polymerization. The person discharged from the polymerization reactor is put into a 0.5 mass% triethylamine aqueous solution to deactivate the polymerization catalyst, and then filtered, washed, and dried. Next, it was fed to a twin-screw extruder (L/D = 40) with a vent set at 200°C, and 0.8 mass% triethylamine was added in the end stabilization zone so that the amount converted to nitrogen became 20 ppm. The aqueous solution was stabilized by degassing under reduced pressure at 90 kPa, and granulated by a granulator. Thereafter, it was dried at 100°C for 2 hr to obtain (A-1) polyacetal resin. The obtained (A-1) polyacetal resin had a melting point of 164°C and a melt flow index of 71 g/10 minutes.

(A-2) The polyacetal resin (A-2) was produced in the same manner as the production method of the (A-1) polyacetal resin except that the flow rate of the methylal as the molecular weight regulator was 9.4 g/hr. The obtained (A-2) polyacetal resin had a melting point of 164°C and a melt flow index of 121 g/10 minutes.

(A-3) The polyacetal resin (A-3) was produced in the same manner as the production method of the (A-1) polyacetal resin except that the flow rate of the methylal as the molecular weight regulator was 10.6 g/hr. The obtained (A-3) polyacetal resin had a melting point of 164°C and a melt flow index of 180 g/10 minutes.

(A-4) The polyacetal resin (A-3) was produced in the same manner as the production method of the (A-1) polyacetal resin except that the flow rate of the methylal as the molecular weight regulator was 4.4 g/hr. The obtained (A-4) polyacetal resin had a melting point of 164°C and a melt flow index of 31 g/10 minutes.

(A-5) Except that the flow rate of methylal as a molecular weight regulator is 11.6 g/hr, (A-5) polyacetal resin is produced in the same manner as the production method of (A-1) polyacetal resin. The obtained (A-5) polyacetal resin had a melting point of 164°C and a melt flow index of 213 g/10 minutes.

[(B) Nitrogen compounds] (B-1) Nylon 66 (molecular weight 10000) (B-2) Melamine (made by Nissan Chemical Industry Co., Ltd.)

[(C) fatty acid metal salt] (C-1)Calcium stearate (C-2) calcium montanate

[Other additives] (D-1) Antioxidant: Triethylene glycol-bis[3-(3-tertiarybutyl-5-methyl-4-hydroxyphenyl) propionate] (Irganox245 manufactured by BASF Corporation)

[Melting Flow Index (MI)] According to ASTM-D-1238, the MELT INDEXER manufactured by Toyo Seiki was used to measure MI (melt flow index: g/10 minutes) under the conditions of 190°C and 2160 g.

[Thermal stability] The polyacetal resin composition (3±0.01 g) obtained by extrusion is heated to 230° C. under a nitrogen atmosphere (50 nl/hr) to melt it, and the formaldehyde gas generated by the residence time of 2 to 30 minutes is absorbed in 1 mol /l of sodium sulfite aqueous solution is obtained by titrating sodium hydroxide produced by sulfuric acid with a concentration of 1/100 equivalent, converted to the amount of formaldehyde gas. In this titration, vanilloid was used as an indicator, and the time point when the blue color became colorless was regarded as the end point.

[Extrusion] The particles of the polyacetal resin composition obtained by extrusion were visually confirmed to be 2.5 kg. The shape in which the particles are connected together is called a continuous particle, and the continuous particle is taken out and the weight is measured. Calculate the ratio and score. The higher the score, the better the extrudability (the larger the continuous particle ratio, the worse the extrudability). 3: No continuous grain 2: The ratio of continuous grains is less than 10% 1: The ratio of continuous grain is more than 50%

[foreign body] The polyacetal resin composition was press-formed into a flat plate using a hot press set at 220°C (made by Matsuda Manufacturing Co., Ltd.) using 180 mm×180 mm×2 mm (thickness) as a mold frame. For both sides of the forming plate, use a magnifying glass to measure the number of foreign objects above 0.1 mm. The foreign body has black, tea, red, yellow and other colors, all counted.

[Dispersibility of metal powder] Using Laboplastomill heated at 170°C, 70 g of 20 μm SUS316L powder and 30 g of polyacetal resin composition obtained in the following examples and comparative examples were kneaded in a semi-melted state 30 In minutes, a standing solid substance (volume 36 cm ³ ) is produced. Cut 5 g of each of the 5 randomly selected parts from the obtained solid. Next, the polyacetal resin composition was degreased in an electric furnace set at 550°C, and the weight of the remaining metal was measured. Furthermore, the ratio of the maximum weight to the minimum weight is obtained. The smaller the ratio, the better the dispersibility.

[Example 1] To 100 parts by mass of (A-1) polyacetal resin, 0.05 parts by mass of (B-1) nylon 66 and 0.3 parts by mass of (C-1) calcium stearate were added and mixed uniformly, and the mixture was set to 200°C. A twin-screw extruder with vent holes (L/D = 40) granulates while degassing under reduced pressure at 90 kPa. Thereafter, it was dried at 100°C for 2 hr. The obtained particles were evaluated, and the results are shown in Table 1.

[Examples 2 to 13] The same operations as in Example 1 were carried out with the composition described in Table 1. The obtained particles were evaluated, and the results are shown in Table 1.

[Comparative Examples 1-9] The same operations as in Example 1 were carried out with the composition described in Table 2. The obtained pellets were evaluated, and the results are shown in Table 2.

[Table 1]

[Table 2]

According to the evaluation results of Tables 1 and 2 above, it is known that (A) polyacetal resin, (B) nitrogen-containing compound, and (C) fatty acid metal salt are contained in a specific content, the melt flow index is in a specific range, and (C) The embodiment in which the ratio of the content of the fatty acid metal salt to the content of the (B) nitrogen-containing compound is within a specific range is excellent in thermal stability, extrudability, and suppression of foreign matter, and is also excellent in dispersibility with metal powder. [Industry availability]

According to the present invention, it is possible to provide a polyacetal resin composition which is excellent in extrudability, thermal stability, and suppression of foreign matter and also in dispersibility with metal powder, and is excellent in extrudability and thermal stability, and contains less foreign matter Furthermore, the metal powder in which the metal powder is effectively dispersed and the metal resin composition of the polyacetal resin composition.

Claims (6)

A polyacetal resin composition, characterized in that it comprises (A) 100 parts by mass of polyacetal resin, (B) 0.005 to 0.2 parts by mass of nitrogen-containing compound and (C) 0.01 to 0.8 parts by mass of fatty acid metal salt, And the melt flow index measured under the conditions of 190°C and 2.16 kg is 60 g/10 minutes or more and less than 200 g/10 minutes, The ratio ((C)/(B)) of the content of the (C) fatty acid metal salt to the content of the (B) nitrogen-containing compound is 1 to 15. The polyacetal resin composition according to claim 1, wherein the ratio ((C)/(B)) of the content of the (C) fatty acid metal salt to the content of the (B) nitrogen-containing compound is 1-10. The polyacetal resin composition according to claim 1, wherein the polyacetal resin (A) is 100 parts by mass relative to the above, The content of the (B) nitrogen-containing compound is 0.005 to 0.1 parts by mass, and the content of the (C) fatty acid metal salt is 0.01 to 0.6 parts by mass. The polyacetal resin composition according to claim 2, wherein, relative to 100 parts by mass of the above (A) polyacetal resin, The content of the (B) nitrogen-containing compound is 0.005 to 0.1 parts by mass, and the content of the (C) fatty acid metal salt is 0.01 to 0.6 parts by mass. The polyacetal resin composition according to any one of claims 1 to 4, further comprising (D) an antioxidant at a content of 0.01 to 1.0 part by mass relative to 100 parts by mass of the (A) polyacetal resin. A metal resin composition comprising a metal powder and the polyacetal resin composition according to any one of claims 1 to 5, and the content of the metal powder is 70 to 95 in 100% by mass of the metal resin composition quality%.