JP2013245257A - Polyamide resin composition and molded article comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin composition having magnetism and showing both improved toughness and durability when immersed in high-temperature water, and to provide a molded article using the composition.SOLUTION: A polyamide resin composition is provided, comprising a polyamide resin, magnetic powder and talc. The composition contains the magnetic powder in an amount of 50 mass% or more and 98 mass% or less with respect to the whole amount of the polyamide resin composition, and contains the talk in an amount of 2 mass% or more and less than 30 mass% with respect to the total amount of the polyamide resin and the talc.

Description

  The present invention relates to a polyamide resin composition having magnetism and a molded body comprising the same.

  A polyamide resin composition having magnetism and a molded body made of the same need to be filled with a large amount of magnetic powder in order to have sufficient magnetism, and specifically, it is necessary to fill the composition with 50% by mass or more. There is. If it does so, since the quantity of a polyamide resin will be less than 50 mass% and the fluidity | liquidity at the time of shaping | molding will become low, generally the molecular weight of a polyamide resin is made small and fluidity | liquidity is improved.

  However, when the molecular weight of the polyamide resin is reduced, the toughness is lowered, and there is a problem that the strength of the molded body using the polyamide resin is not sufficient.

  In contrast, Patent Document 1 discloses a technique for improving the fluidity of a polyamide resin composition having magnetism, and Patent Document 2 adds an elastomer to a polyamide resin composition having magnetism. A technique for improving the toughness of a polyamide resin composition having magnetism is disclosed.

JP-A-8-217970 JP 2004-352791 A

  However, conventional techniques have not provided a polyamide resin composition having magnetism that improves both toughness and durability when immersed in high-temperature water.

  Therefore, an object of the present invention is to provide a polyamide resin composition having magnetism with improved toughness and durability when immersed in high-temperature water, and a molded body using the same.

  The present inventors have found that a polyamide resin composition containing a specific amount of magnetic powder and a specific amount of talc can achieve the above-mentioned problems.

  That is, the present invention is a polyamide resin composition comprising a polyamide resin, a magnetic powder and talc, wherein the magnetic powder is contained in an amount of 50% by mass to 98% by mass with respect to the total amount of the polyamide resin composition. A polyamide resin composition containing 2% by mass or more and less than 30% by mass of the talc with respect to the total amount of talc.

  According to the present invention, it is possible to provide a polyamide resin composition having magnetism with improved toughness and durability when immersed in high-temperature water, and a molded body using the same.

  The present invention is a polyamide resin composition containing a polyamide resin, a specific amount of magnetic powder and a specific amount of talc, and a molded body using the same.

[Polyamide resin]
The polyamide resin used in the present invention has an amide bond (-CONH-) in the main chain, and a lactam, aminocarboxylic acid, or a nylon salt composed of diamine and dicarboxylic acid or diamine and dibutyl oxalate as raw materials, It can be obtained by polymerization or copolymerization by a known method such as melt polymerization, solution polymerization or solid phase polymerization.

  Examples of the lactam include ε-caprolactam, ω-enantolactam, ω-laurolactam, α-pyrrolidone, α-piperidone and the like. These can use 1 type (s) or 2 or more types. Among these, ε-caprolactam and / or ω-laurolactam are preferable.

  Examples of aminocarboxylic acids include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. These can use 1 type (s) or 2 or more types. Among these, at least one selected from the group consisting of 6-aminocaproic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid is preferable.

  Examples of diamines include ethylene diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, peptamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecane methylene diamine, tridecane diamine, and tetradecane diamine. , Pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, eicosanediamine, 2-methyl-1,8-octanediamine, 2,2,4 / 2,4,4-trimethylhexamethylenediamine, etc. Aliphatic diamine, 1,3- / 1,4-cyclohexyldiamine, bis (4-aminocyclohexyl) methane, bis (4-aminocyclohexyl) propane, bis (3 Methyl-4-aminocyclohexyl) methane, (3-methyl-4-aminocyclohexyl) propane, 1,3- / 1,4-bisaminomethylcyclohexane, 5-amino-2,2,4-trimethyl-1-cyclo Cycloaliphatic diamines such as pentanemethylamine, 5-amino-1,3,3-trimethylcyclohexanemethylamine, bis (aminopropyl) piperazine, bis (aminoethyl) piperazine, norbornanedimethyleneamine, m / p-xyl Examples thereof include aromatic diamines such as range amines. These can use 1 type (s) or 2 or more types. Among these, at least one selected from the group consisting of hexamethylenediamine, nonanediamine and 2-methyl-1,8-octanediamine is preferable.

  Dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecane Aliphatic dicarboxylic acids such as dionic acid, hexadecanedioic acid, octadecanedioic acid, eicosandioic acid, 1,3- / 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4′-dicarboxylic acid, norbornane dicarboxylic acid And alicyclic dicarboxylic acids such as isophthalic acid, terephthalic acid, and aromatic dicarboxylic acids such as 1,4- / 1,8- / 2,6- / 2,7-naphthalenedicarboxylic acid. These can use 1 type (s) or 2 or more types. Among these, oxalic acid and / or adipic acid are preferable.

  These lactams, aminocarboxylic acids, diamines and dicarboxylic acids, or polyamide resins composed of diamines and dibutyl oxalate, or copolymers thereof, can be used alone or in the form of a mixture.

  As a single polymer of polyamide resin, for example, polycaprolactam (polyamide 6), polyundecanoic acid lactam (polyamide 11), polylauryl lactam (polyamide 12), polyethylene adipamide (polyamide 26), polytetramethylene succinamide (Polyamide 44), polytetramethylene glutamide (polyamide 45), polytetramethylene adipamide (polyamide 46), polytetramethylene azelamide (polyamide 49), polytetramethylene sebamide (polyamide 410), polytetramethylene Dodecamide (polyamide 412), polypentamethylene succinamide (polyamide 54), polypentamethylene glutamide (polyamide 55), polypentamethylene adipamide (polyamide 56), polypentamethylene Ramide (polyamide 59), polypentamethylene sebacamide (polyamide 510), polypentamethylene dodecamide (polyamide 512), polyhexamethylene succinamide (polyamide 64), polyhexamethylene glutamide (polyamide 65), polyhexa Methylenediaminoadipamide (polyamide 66), polyhexamethylene azelamide (polyamide 69), polyhexamethylene sebamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polynonamethylene adipamide (polyamide 96) ), Polynonamethylene azelamide (polyamide 99), polynonamethylene sebamide (polyamide 910), polynonamethylene dodecamide (polyamide 912), polydecamethylene adipamide (polyamide 106), Ridecamemethylene amide (polyamide 109), polydecamethylene decanamide (polyamide 1010), polydecamethylene dodecamide (polyamide 1012), polydodecamethylene adipamide (polyamide 126), polydodecamethylene azeamide (polyamide 129) Polydodecamethylene sebacamide (polyamide 1210), polydodecamethylene dodecamide (polyamide 1212), polyamide 92, polyamide 102, polyamide 122, polyamide 62, and the like.

  Examples of the copolymer of the polyamide resin using lactam, aminocarboxylic acid, diamine, dicarboxylic acid and / or dibutyl oxalate include, for example, caprolactam / hexamethylenediaminoadipic acid copolymer (polyamide 6/66), caprolactam / Hexamethylene diamino azelaic acid copolymer (polyamide 6/69), caprolactam / hexamethylene diamino sebacic acid copolymer (polyamide 6/610), caprolactam / hexamethylene diaminoundecanoic acid copolymer (polyamide 6/611), caprolactam / Hexamethylene diaminododecanoic acid copolymer (polyamide 6/612), caprolactam / aminoundecanoic acid copolymer (polyamide 6/11), caprolactam / lauryl lactam copolymer (polyamide 6/12) Caprolactam / hexamethylenediaminoadipic acid / lauryllactam (polyamide 6/66/12), caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminosebacic acid (polyamide 6/66/610), and caprolactam / hexamethylenediaminoadipic acid / Examples include hexamethylene diaminododecanedicarboxylic acid (polyamide 6/66/612), polyamide 92/62, polyamide 102/62, polyamide 122/62, and the like.

  Among these, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 1010, polyamide 1012, polyamide 11, polyamide 12, polyamide 92, polyamide 102, polyamide 122, polyamide 62, and copolymers thereof are selected. At least one selected from the group consisting of polyamide 6, polyamide 11, polyamide 12, polyamide 92, polyamide 102, polyamide 122, polyamide 62 and copolymers thereof is more preferable, and polyamide 6, polyamide 11, at least one selected from the group consisting of polyamide 12, polyamide 92, polyamide 102, polyamide 122, polyamide 62 and copolymers thereof is more preferable. 11, at least one and more preferably selected from the group consisting of polyamide 12 and polyamide 6/12.

  The relative viscosity of the polyamide resin measured according to JIS K-6920 is 1.40 from the viewpoint of the fluidity of the polyamide resin composition, the dispersion of the magnetic powder in the polyamide resin composition, and the mechanical properties of the polyamide resin composition. It is preferably 1.80 or less, more preferably 1.45 or more and 1.75 or less, and further preferably 1.50 or more and 1.70 or less.

  The terminal carboxyl group concentration of the polyamide resin is preferably 90 μeq / g or less, preferably 10 μeq / g or more and 80 μeq / g or less, from the viewpoint of improving the stability of the viscosity at the time of molding the polyamide resin composition. 20 μeq / g or more and 70 μeq / g or less is more preferable.

  The terminal amino group concentration of the polyamide resin is preferably 30 μeq / g or less, more preferably 5 μeq / g or more and 25 μeq / g or less, from the viewpoint of moldability of the polyamide resin composition, and 5 μeq / g or more and 20 μeq or less. More preferably, it is in the range of / g or less.

  The terminal carboxyl group concentration (μeq / g) can be measured by dissolving a polyamide resin in benzyl alcohol and titrating with 0.05 N (normal) sodium hydroxide solution. The terminal amino group concentration (μeq / g) can be measured by dissolving a polyamide resin in a phenol / methanol mixed solution and titrating with 0.05 N (normal) hydrochloric acid.

  The terminal adjustment of the polyamide resin is produced by polymerization or copolymerization by a conventional method, for example, a known method such as melt polymerization, solution polymerization or solid phase polymerization in the presence of a terminal adjusting agent. Alternatively, it is produced by melt-kneading in the presence of amines after polymerization. Alternatively, it is produced by melt-kneading in the presence of a terminal adjusting agent after polymerization. As described above, the terminal adjusting agent can be added at any stage during the polymerization, or at any stage during the melt kneading after the polymerization, but in consideration of the fluidity and moldability of the polyamide resin composition, It is preferable to add at this stage.

  In adjusting the terminal of the polyamide resin, one or more of monoamine, diamine, monocarboxylic acid and dicarboxylic acid can be added as appropriate. For example, alicyclic such as aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, cyclohexylamine, dicyclohexylamine Aromatic monoamines such as monoamine, aniline, toluidine, diphenylamine, and naphthylamine, aliphatic diamines such as hexamethylenediamine, nonamethylenediamine, decamethylenediamine, and dodecamethylenediamine, cycloaliphatic diamines such as cyclohexanediamine, methylcyclohexanediamine, and isophoronediamine Aromatic diamines such as diamine, m- / p-phenylenediamine, m- / p-xylylenediamine, acetic acid, propionic acid, butyric acid, Acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, isobutyric acid and other aliphatic monocarboxylic acids, cyclohexanecarboxylic acid and other alicyclic monocarboxylic acids, benzoic acid Aromatic monocarboxylic acids such as toluic acid, α- / β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, phenylacetic acid, adipic acid, trimethyladipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid , Aliphatic dicarboxylic acids such as dodecane dicarboxylic acid, alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, 1,3- / 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, 1,4- Aromatic dicals such as / 2,6- / 2,7-naphthalenedicarboxylic acid It is phosphate and the like. These can use 1 type (s) or 2 or more types. The amount of these end modifiers varies depending on the reactivity of the end modifier and the polymerization conditions, but the relative viscosity, terminal carboxyl group concentration, and terminal amino group concentration of the polyamide resin to be finally obtained are within the above ranges. As appropriate.

  From the viewpoint of manufacturability and moldability of the polyamide resin composition, the polyamide resin is preferably contained in an amount of 2% by mass or more and 49% by mass or less, and preferably 3% by mass or more and 35% by mass or less based on the total amount of the polyamide resin composition. Is more preferable, and it is further more preferable to contain 5 mass% or more and 30 mass% or less.

[Magnetic powder]
The magnetic powder used in the present invention is not particularly limited as long as it has magnetism and can be used for a plastic magnet, and is selected from the group consisting of ferrite magnetic powder, alnico magnetic powder, and rare earth magnetic powder. At least one selected from the above is preferable, and ferrite magnetic powder is more preferable.

  Examples of the ferrite-based magnetic powder include barium ferrite powder and strontium ferrite powder, and strontium ferrite powder is more preferable.

  Examples of the alnico magnetic powder include alnico magnetic powder composed of nickel, aluminum, cobalt, and copper, and alnico magnetic powder composed of nickel, aluminum, cobalt, copper, and titanium.

  Examples of rare earth magnetic powders include magnetic powder of samarium cobalt, magnetic powder obtained by replacing the cobalt component of samarium cobalt with copper, iron, titanium, zirconium, nafnium, niobium, tantalum, etc., neodymium-iron-boron magnetic powder, and the like. .

  These magnetic powders can be used alone or in combination of two or more.

  The average particle size of the magnetic powder is preferably 0.1 μm or more and 300 μm or less, more preferably 0.1 μm or more and 200 μm or less, from the viewpoint of fluidity and mechanical strength of the polyamide resin composition of the present invention. More preferably, it is 0.5 μm or more and 100 μm or less. When the average particle size of the magnetic metal powder exceeds 300 μm, the fluidity and mechanical strength of the polyamide resin composition may be lowered.

  The magnetic powder is contained in an amount of 50% by mass to 98% by mass, preferably 65% by mass to 97% by mass, and more preferably 70% by mass to 95% by mass with respect to the total amount of the polyamide resin composition. When the content is less than 50% by mass, the residual magnetic flux density is low, the practicality as a permanent magnet application is small, and the effect on the flow characteristics of the resin may be small. On the other hand, if it exceeds 98% by mass, the magnetic field orientation is inferior, the residual magnetic flux density is not improved due to the decrease in the resin component, and the amount of resin is small, so the fluidity is inferior, and this is filled in the kneading and molding process. It may cause troubles such as defects and lack practicality.

  From the viewpoint of improving dispersibility in the polyamide resin composition and / or adhesion to the polyamide resin, the magnetic powder may be treated in advance with a coupling agent, a surface modifier, or the like.

  Coupling agents or surface modifiers include silane compounds, titanate compounds, aluminum compounds, chromium compounds, methacrylate compounds, organophosphorus compounds such as phosphites, and surface modification agents. Agents can be used. Among these, from the viewpoint of enhancing the compatibility with the polyamide resin, a silane compound and / or titanate compound containing an amino group is preferable. These can be appropriately selected depending on the type of polyamide resin used.

  Examples of silane compounds containing amino groups include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-. Aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminodithiopropyltrihydroxysilane, γ- (polyethyleneamino) propyltrimethoxysilane, N-β- (aminopropyl) ) -Γ-aminopropylmethyldimethoxysilane, N- (trimethoxysilylpropyl) -ethylenediamine, γ-dibutylaminopropyltrimethoxysilane and the like. These can use 1 type (s) or 2 or more types.

  As titanate compounds, isopropyl triisostearoyl titanate, isopropyl tri (N-aminoethyl) titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraisopropyl titanate, tetrabutyl titanate, tetrabutyl titanate, Octyl bis (ditridecyl phosphite) titanate, isopropyl trioctanoyl titanate, isopropyl tridodecyl benzene sulfonyl titanate, isopropyl tri (dioctyl phosphate) titanate, bis (dioctyl pyrophosphate) ethylene titanate, isopropyl dimethacrylisostearoyl titanate, tetra (2 , 2-Diallyloxymethyl-1-butyl) bis ( Tridecyl phosphite) titanate, isopropyl tricumylphenyl titanate, bis (dioctyl pyrophosphate) oxy acetate titanate, and isopropyl isostearoyl diacryl titanate. These can use 1 type (s) or 2 or more types.

[talc]
The talc (talc) used in the present invention contains Mg ₃ Si ₄ O ₁₀ (OH) ₂ as a main component. From the viewpoint of improving toughness and durability when immersed in high-temperature water, it is preferable that Mg ₃ Si ₄ O ₁₀ (OH) ₂ is contained in an amount of 50% by mass to 100% by mass with respect to the total amount of talc, and 70% by mass. It is more preferable that it is contained in an amount of 100% by mass or more and 100% by mass or less.

  The average particle size of talc is not particularly limited, but is preferably 20 μm or less from the viewpoint of the appearance and impact strength of the molded product, and is preferably 3 to 15 μm from the viewpoint of bondability with metal. For example, talc is collected in accordance with, for example, the Japanese Industrial Standard Flour Mixture-Sampling Method General Rules (JIS M8100), and the Sample Preparation General Rules for Measuring Fine Ceramic Raw Material Particle Size Distribution (JIS R 1622-1995). The talc is prepared as a measurement sample according to), and can be measured according to the particle size distribution measurement method (JIS R 1629-1997) of the fine ceramic raw material by the laser diffraction / scattering method. As the apparatus, a laser diffraction particle size distribution analyzer SALD-7000 manufactured by Shimadzu Corporation can be used.

  As the talc, surface-treated talc can be used, and talc that has been treated in the same manner as the magnetic powder may be used.

  From the viewpoint of improving toughness and durability when immersed in high-temperature water, the talc content may be 2% by mass or more and less than 30% by mass and 2% by mass or more and 29% by mass or less with respect to the total amount of the polyamide resin and talc. Preferably, it is more preferably 2% by mass or more and 25% by mass or less, further preferably 5% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 10% by mass or less.

[Polyamide resin composition]
In the polyamide resin composition of the present invention, various additives, modifiers, reinforcing materials such as heat stabilizers, antioxidants and the like that are usually blended within the range that does not impair the properties of the polyamide resin composition of the present invention. Agent, ultraviolet absorber, weathering agent, filler, plasticizer, foaming agent, anti-blocking agent, tackifier, sealing property improver, cloud proofing agent, mold release agent, crosslinking agent, foaming agent, flame retardant, colorant (Pigments, dyes, etc.), coupling agents, inorganic reinforcing materials such as glass fibers, and the like can be contained. From the viewpoint of improving the fluidity, moldability and magnetic properties of the polyamide resin composition, it is preferable to contain a lubricant and a stabilizer.

  Lubricants include waxes such as paraffin wax, polyethylene wax, polypropylene wax, carnauba wax and microcrystalline wax, fatty acids such as stearic acid, lauric acid, palmitic acid and oleic acid, zinc stearate, calcium stearate and barium stearate. , Aluminum stearate, magnesium stearate, lithium stearate, calcium laurate, zinc linoleate, calcium ricinoleate, zinc 2-ethylhexanoate, etc. (metal soaps), stearic acid amide, oleic acid amide, erucic acid amide , Behenic acid amide, palmitic acid amide, lauric acid amide, hydroxy stearic acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide, ethyl Bis lauric acid amide, distearyl adipic acid amide, ethylene bis oleic acid amide, dioleyl adipic acid amide and other fatty acid amides, fatty acid esters such as butyl stearate, ethylene glycol, stearyl alcohol and other alcohols, polyethylene glycol, polypropylene glycol, poly Polyethylenes such as tetramethylene glycol and modified products thereof, dimethylpolysiloxane, silicone grease, fluorine compounds such as fluorine oil, fluorine grease, fluorine-containing resin powder, silicon nitride, silicon carbide Inorganic compound powders such as magnesium oxide, silica, alumina, and molybdenum disulfide. These can use 1 type (s) or 2 or more types.

  Examples of the stabilizer include pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl). -4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], ethylenebis (oxyethylene) bis [3- ( 5-t-butyl-4-hydroxy-m-tolyl) propionate], N, N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamide), 3,9-bis [1,1-dimethyl-2- {β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl] -2,4 Hindered phenolic antioxidants such as 8,10-tetrachiosaspiro [5,5] undecane, didodecyl-3,3′-thiodipropionate, dioctadecyl-3,3′-thiodipropionate, thio Sulfur-based antioxidants such as diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], tris (2,4-di-t-butylphenylphosphite), bis (2, Phosphorus processing stabilizers such as 4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl succinate and 4-hydroxy- A hindered amine light stabilizer such as a polymer of 2,2,6,6-tetramethyl-1-piperidineethanol, 2,4-di-t-butyl-6- (5- UV absorbers such as chlorobenzotriazol-2-yl) phenol and 2- (2H-benzotriazol-2-yl) -4,6-di-t-pentylphenol, N, N′-bis [3,5- And metal inactive agents such as di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and flame retardants such as melamine cyanurate. These can use 1 type (s) or 2 or more types.

  Although the manufacturing method of the polyamide resin composition of this invention is demonstrated, it does not specifically limit to the manufacturing method described below. Although the polyamide resin composition can be produced by a mixing process, it is preferably produced through a mixing process and a kneading process from the viewpoint of dispersion of talc and magnetic powder in the polyamide resin composition.

  The mixing step is a step of mixing polyamide resin, talc, magnetic powder, and various additives as required, by a known method. The mixer used in the known method is not particularly limited, and examples thereof include a ribbon mixer, a V-type mixer, a rotary mixer, a Henschel mixer, a flash mixer, a nauta mixer, and a tumbler. Rotating ball mill, vibrating ball mill, planetary ball mill, wet mill, jet mill, hammer mill, cutter mill and the like. In addition, the use of a solvent at the time of mixing is an effective means in terms of uniform mixing when mixing the coupling agent and / or lubricant, but is not always necessary. In the mixing step, the shape of the polyamide resin to be used may be any of pellets, beads, powders, pastes, and the like. From the viewpoint of improving the homogeneity of the polyamide resin composition, a powder having an average particle size of 1 mm or less is preferable. In addition, it is preferable to perform a mixing process before a kneading | mixing process.

  The kneading process consists of polyamide resin, magnetic powder, talc, and various additives as required. Batch type kneaders such as Brabender, Banbury mixer, Henschel mixer, helical rotor, roll, single screw extruder, twin screw extruder Is a step of kneading in a temperature range of 120 ° C. or higher and 400 ° C. or lower. The kneading temperature is generally selected from a temperature range where the polyamide resin melts and does not decompose. The kneaded polyamide resin composition is extruded into a strand or a sheet, and the cut product such as hot cut and underwater cut is applied to a pulverizer, or the cooled and solidified block is applied to a pulverizer. Thus, it is preferable to form pellets or particles (powder) so as to be easily formed into a molded body.

[Molded body]
In order to obtain a molded product from the polyamide resin composition of the present invention, a molding process is further performed. (Molding process). As a method of obtaining a molded body from the polyamide resin composition of the present invention, the polyamide resin composition of the present invention is mixed in a molding machine, mixed, melt-kneaded and molded into a desired shape, mixed, There is a two-stage molding method in which a melting process is performed and then molding is performed using a molding machine different from the equipment used in the mixing and melting processes. Examples of the molding method include injection molding, extrusion molding, and compression molding.

  From the viewpoint of molding a molded article having high magnetic properties, the molding method of the present invention is made by injection-moulding, extrusion molding, compression while heating and melting the polyamide resin composition of the present invention and applying a magnetic field as necessary. The method of shaping | molding is mentioned. In the case of extrusion molding, it can be performed together with the kneading step. Among these molding methods, injection molding is preferable from the viewpoint of obtaining a molded body excellent in surface smoothness and magnetic properties. The molding temperature is the same as the kneading temperature.

  The obtained molded body is usually further magnetized to enhance the performance as a permanent magnet. Magnetization is performed by an ordinary method such as an electromagnet that generates a static magnetic field, a condenser magnetizer that generates a pulsed magnetic field, or the like. The magnetic field strength at this time is preferably 15 kOe (1.2 MA / m) or more, and more preferably 30 kOe (2.4 MA / m) or more.

  Hereinafter, the present invention will be described in more detail with reference to embodiments. However, the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

Below, the material used for an embodiment is shown.
[material]
(1) Polyamide resin Relative viscosity 1.67 obtained by polymerizing ω-laurolactam or 12-aminododecanoic acid and aliphatic monocarboxylic acid, terminal carboxyl group concentration 65 μeq / g, terminal amino group concentration 18 μeq / g A powder having an average particle diameter of 1 mm or less that passes through a 12 mesh screen mesh of polyamide 12 is used. (Hereinafter also referred to as polyamide 12)

(2) Magnetic powder Average particle diameter is 1.3 μm, BET specific surface area is 1.6 m ² / g, and β- (aminoethyl) -γ-aminopropyltrimethoxysilane is 1.0 mass relative to 100 parts by mass of strontium ferrite. The strontium ferrite surface-treated at the part is used. (Hereinafter also referred to as strontium ferrite.)

(3) Talc Shimgon M manufactured by Nippon Talc Co., Ltd., which is talc having an average particle diameter of 8 μm, is used. (Hereafter, also called talc.)

[Embodiment 1]
19% by mass of polyamide 12, 80% by mass of strontium ferrite and 1% by mass of talc (talc is 5% by mass with respect to the total amount of polyamide 12 and talc) are stirred and mixed with a Henschel mixer, and kneaded with a twin screw extruder. Extrusion to obtain pellets of the polyamide resin composition. Using the obtained polyamide resin composition, a test piece having dimensions of 127 mm × 12.7 mm × 6.5 mm is prepared by injection molding under conditions of a cylinder temperature of 290 ° C. and a mold temperature of 80 ° C. When the bending test at 23 ° C. according to ASTM D-790 is performed using the test piece, the bending strength becomes 130 to 135 MPa. In addition, using the resulting polyamide resin composition, a test piece for measuring Izod impact strength having dimensions of 62 mm × 12.7 mm × 12.7 mm was prepared by injection molding at a cylinder temperature of 290 ° C. and a mold temperature of 80 ° C. To do. According to ASTM D-256, a notch is made in the test piece, and the Izod impact strength is measured at 23 ° C., it becomes 55 to 65 MPa. Further, a test piece for measuring bending strength and Izod impact strength is prepared, and the test piece is immersed in hot water at 80 ° C. for 1000 hours. When the test piece is taken out and the bending strength and Izod impact strength are measured according to the above methods, the bending strength and Izod impact strength are 115 to 125 MPa and 75 to 85 MPa, respectively.

[Embodiment 2]
In the first embodiment, a polyamide resin is obtained in the same manner as in the first embodiment except that the polyamide 12 is 18% by mass and the talc is 2% by mass (the talc is 10% by mass with respect to the total amount of the polyamide 12 and talc). A pellet of the composition is obtained. When the same evaluation as in Embodiment 1 was performed using the obtained polyamide resin composition, the bending strength was 135 to 140 MPa, the Izod impact strength was 60 to 70 MPa, and the hot water at 80 ° C. was 1000 The bending strength and Izod impact strength after time immersion are 120 to 130 MPa and 80 to 90 MPa, respectively.

[Embodiment 3]
In the first embodiment, a polyamide resin is obtained in the same manner as in the first embodiment except that the polyamide 12 is 16% by mass and the talc is 4% by mass (the talc is 20% by mass with respect to the total amount of the polyamide 12 and talc). A pellet of the composition is obtained. When the same evaluation as in Embodiment 1 was performed using the obtained polyamide resin composition, the bending strength was 135 to 140 MPa, the Izod impact strength was 60 to 70 MPa, and the hot water at 80 ° C. was 1000 The bending strength and Izod impact strength after time immersion are 120 to 130 MPa and 80 to 90 MPa, respectively.

[Comparison]
Even if the talc is not added and the polyamide 12 is made 20% by mass, the polyamide resin composition obtained has a bending strength of 120 to 125 MPa and an Izod impact strength of 95 to 105 MPa even in the same manner as in the first embodiment. The bending strength and the Izod impact strength after 1000 hours of immersion in hot water at 80 ° C. are 90 to 110 MPa and 30 to 40 MPa, respectively, which are inferior to the embodiment.

  Further, the polyamide resin composition obtained is the same as in Embodiment 1 except that talc is 6% by mass, polyamide 12 is 14% by mass, and talc is 30% by mass with respect to the total amount of polyamide 12 and talc. The bending strength is 115 to 125 MPa, the Izod impact strength is 40 to 50 MPa, and the bending strength and Izod impact strength after being immersed in hot water at 80 ° C. for 1000 hours are 110 to 120 MPa and 50 respectively. ˜60 MPa, both bending strength and Izod impact strength are inferior to the embodiment.

  Furthermore, except that the talc is wollastonite, the polyamide resin composition obtained has a flexural strength of 120 to 125 MPa, an Izod impact strength of 45 to 55 MPa, and 80 ° C. The bending strength and Izod impact strength after 1000 hours of immersion in hot water are 90 to 110 MPa and 20 to 30 MPa, respectively, which are inferior to the embodiment.

  Even if the talc is kaolin, even if it is the same as in Embodiment 2, the resulting polyamide resin composition has a bending strength of 115 to 125 MPa, an Izod impact strength of 45 to 55 MPa, and is heated to 80 ° C. hot water. The bending strength and Izod impact strength after 1000 hours of immersion are 90 to 110 MPa and 25 to 35 MPa, respectively, which is inferior to the embodiment.

Claims (5)

A polyamide resin composition comprising a polyamide resin, magnetic powder and talc;
The magnetic powder is contained in an amount of 50% by mass to 98% by mass with respect to the total amount of the polyamide resin composition,
A polyamide resin composition comprising 2% by mass or more and less than 30% by mass of the talc with respect to the total amount of the polyamide resin and the talc. The polyamide resin composition according to claim 1, wherein the magnetic powder is contained in an amount of 65% by mass to 97% by mass with respect to the total amount of the polyamide resin composition. The polyamide resin composition according to claim 1 or 2, wherein the magnetic powder is at least one selected from the group consisting of ferrite magnetic powder, alnico magnetic powder, and rare earth magnetic powder. The polyamide resin composition according to any one of claims 1 to 3, wherein the polyamide resin is at least one selected from the group consisting of polyamide 11, polyamide 12, and polyamide 6/12. The molded object using the polyamide resin composition of any one of Claims 1-4.