Polyamide resin composition and method for producing same

Abstract

To provide a comparatively inexpensive polyamide resin composition excellent in slidable characteristic and mechanical characteristic dispensing with a fluorine-based resin which is general as a slide member.SOLUTION: A polyamide resin composition includes: (A) 100 pts. mass of a polyamide resin; (B) 1-15 pts. mass of a graft copolymer obtained by grafting a side chain including polystyrene or acrylonitrile to a main chain including polyethylene; (C) 0.01-5 pts. mass of a copper compound; and (D) 0.05-5 pts. mass of a metal halide of a metal selected from the group consisting of alkali metals, and alkali earth metals.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyamide resin composition and a method for producing the same. [Background technology]

[0002] Polyamide resins have been widely used as materials for various parts in industrial materials, automobiles, electrical and electronic equipment, industrial applications, etc., due to their excellent sliding properties, moldability, mechanical properties, and chemical resistance.

[0003] Another commonly known method for improving the sliding properties of polyamide resins is to compound and knead a composition containing a solid lubricant such as a fluorine-based resin, graphite, or molybdenum disulfide. For example, Patent Documents 2 to 4 disclose polyamide resin compositions containing a fluorine-based resin. In recent years, the use of resins instead of metal components has been accelerating in the automotive, electrical and electronics fields, and particularly in the automotive field, where weight reduction, cost reduction, and assembly process streamlining are essential to improve fuel economy, there is a demand for molding materials that have superior sliding properties and mechanical properties such as toughness and impact resistance.

[0004] On the other hand, restrictions on the production, import, and use of perfluorooctanoic acid (PFOA), its salts, and PFOA-related substances are being implemented, making it difficult to ensure a stable supply in the future.

[0005] Therefore, a sliding component for a power transmission guide has been proposed in which a graft copolymer is dispersed in a polyamide resin without blending a solid lubricant such as a fluorine-based resin, which is a common method for further improving sliding properties (see Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-117848 [Patent Document 2] International Publication No. 2013 / 047625 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-84679 [Patent Document 4] Japanese Patent Application Laid-Open No. 2012-102189 Summary of the Invention [Problem to be solved by the invention]

[0007] Blending fluororesin with polyamide resin has been proposed to improve sliding properties. For example, a polyamide resin composition in which polytetrafluoroethylene is finely dispersed is commonly known. However, restrictions on the manufacture, import, and use of perfluorooctanoic acid and its salts, as well as PFOA-related substances, are being implemented not only internationally but also domestically under the Chemical Substances Control Law, making it difficult to ensure a stable supply in the future.

[0008] Furthermore, when polytetrafluoroethylene, for example, is used as a fluorine-based resin, in order to finely disperse it, it is necessary to melt-knead it under high shear conditions at a temperature equal to or higher than the melting point of polytetrafluoroethylene, which causes a problem of deterioration of the polyamide resin and a decrease in mechanical strength.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polyamide resin composition which is excellent in sliding properties and mechanical properties and is not restricted by the temperature during melt-kneading, and a method for producing the same. [Means for solving the problem]

[0010] The present invention includes the following aspects. (1) (A) polyamide resin, (B) a graft copolymer in which a side chain containing polystyrene or acrylonitrile is grafted onto a main chain containing polyethylene; (C) a copper compound, and (D) containing a halide of a metal selected from the group consisting of alkali metals and alkaline earth metals; With respect to 100 parts by mass of the (A) polyamide resin, the content of the (B) graft copolymer is 1 to 15 parts by mass, the content of the (C) copper compound is 0.01 to 5 parts by mass, The polyamide resin composition contains 0.05 to 5 parts by mass of the (D) halide of a metal selected from the group consisting of alkali metals and alkaline earth metals. (2) The polyamide resin composition according to (1) above, further comprising 0.01 to 5 parts by mass of a hindered phenol-based heat stabilizer per 100 parts by mass of the (A) polyamide resin. (3) The polyamide resin composition according to (1) or (2) above, further comprising 1 to 30 parts by mass of a fibrous filler per 100 parts by mass of the polyamide resin (A). (4) The polyamide resin composition according to any one of (1) to (3) above, which does not contain perfluorooctanoic acid or its salts in an amount of 10 ppb by mass or more. (5) preparing a masterbatch containing (C) a copper compound and (D) a halide of a metal selected from the group consisting of alkali metals and alkaline earth metals; and a step of melt-kneading the masterbatch, (A) a polyamide resin, and (B) a graft copolymer; A method for producing the polyamide resin composition according to any one of (1) to (4) above, comprising: (6) The method for producing a polyamide resin composition according to (5) above, wherein the melt-kneading temperature is 280°C or higher. [Effects of the Invention]

[0011] According to the present invention, a polyamide resin composition can be obtained which has excellent sliding properties and an excellent balance of mechanical properties such as toughness and impact resistance. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a photograph of a reference example used in evaluating the appearance of wear marks in the following examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0014] The polyamide resin composition of this embodiment contains (A) a polyamide resin, (B) a graft copolymer in which side chains containing polystyrene or acrylonitrile are grafted onto a main chain containing polyethylene, (C) a copper compound, and (D) a halide of a metal selected from the group consisting of alkali metals and alkaline earth metals. In the polyamide resin composition of the present embodiment, the content of the (B) graft copolymer is 1 to 15 parts by mass, the content of the (C) copper compound is 0.01 to 5 parts by mass, and the content of the (D) halide of a metal selected from the group consisting of alkali metals and alkaline earth metals is 0.05 to 5 parts by mass, relative to 100 parts by mass of the (A) polyamide resin. Each component of this embodiment will be described below.

[0015] (A) Polyamide resin Examples of (A) polyamide resins include, but are not limited to, polyamides obtained by ring-opening polymerization of lactams, polyamides obtained by self-condensation of ω-aminocarboxylic acids, polyamides obtained by condensing diamines and dicarboxylic acids, and copolymers thereof. As the (A) polyamide resin, only one of the above polyamides may be used alone, or two or more of them may be used as a mixture.

[0016] Specific examples of the polyamide resin (A) include, but are not limited to, polyamide 4 (poly-α-pyrrolidone), polyamide 6 (polycaproamide), polyamide 11 (polyundecaneamide), polyamide 12 (polydodecanamide), polyamide 46 (polytetramethylene adipamide), polyamide 66 (polyhexamethylene adipamide), polyamide 610 (polyhexamethylene sebacamide), polyamide 612 (polyhexamethylene dodecamide), polyamide 6T ( Examples of suitable polyamides include poly(hexamethylene terephthalamide), polyamide 9T (polynonamethylene terephthalamide), polyamide 6I (polyhexamethylene isophthalamide), polyamide 2Me5T (poly-2-methylpentamethylene terephthalamide (Me is a methyl group, the same applies hereinafter)), polyamide MXD6 (polymetaxylylene adipamide), and polyamide PXD12 (polyparaxylylene dodecamide), as well as copolymer polyamides containing at least one of these as a constituent component.

[0017] In terms of sliding properties, the polyamide resin (A) of this embodiment is preferably a polyamide resin whose main component is polyamide 66, polyamide 6, polyamide 610, or polyamide 612. Here, "main component" means that the content of the main component relative to the total mass of the polyamide resin (A) is 50 mass% or more. Furthermore, in terms of heat resistance, the polyamide resin (A) is preferably a polyamide resin whose main component is polyamide 66 or polyamide PXD12, and more preferably a polyamide resin whose main component is polyamide 66.

[0018] The relative viscosity in sulfuric acid of the (A) polyamide resin is preferably 2.0 or more, more preferably 2.1 or more, even more preferably 2.3 or more, and most preferably 3.2 or more, and the relative viscosity in sulfuric acid of the (A) polyamide resin is preferably 4.5 or less, more preferably 4.4 or less, and most preferably 4.3 or less. When the relative viscosity in sulfuric acid is 2.0 or more, a polyamide resin composition having better mechanical properties tends to be obtained, and when the relative viscosity in sulfuric acid is 4.5 or less, a polyamide resin composition having better flowability and processability tends to be obtained. The sulfuric acid relative viscosity can be measured by the method according to JIS-K6920 shown in the examples.

[0019] (B) Graft copolymer The graft copolymer (B) in this embodiment is a graft copolymer in which side chains containing polystyrene or acrylonitrile are grafted onto a main chain containing polyethylene, and is preferably a graft copolymer in which a vinyl polymer such as an acrylonitrile-styrene copolymer or polystyrene is graft copolymerized as a side chain onto an olefin polymer (preferably polyethylene) containing polyethylene as a main chain. The presence of the (B) graft copolymer contributes to improving the sliding properties of the resulting polyamide resin composition.

[0020] The method for preparing the (B) graft copolymer is not particularly limited, and it can be easily prepared by a known radical reaction. For example, the graft copolymer can be prepared by adding a radical catalyst to a monomer constituting an olefin polymer component including polyethylene and a monomer constituting a vinyl polymer, kneading them together to form a graft, or by adding a radical catalyst such as a peroxide to either the olefin polymer component or the vinyl polymer component to form a free radical, which is then melt-kneaded with the polymer of the other component to form a graft. By graft copolymerizing an olefin copolymer containing polyethylene as the main chain with a vinyl polymer containing polystyrene or acrylonitrile as a side chain, peeling near the exit during injection molding can be prevented.

[0021] The ratio of (b1) the olefin polymer to (b2) the vinyl polymer constituting (B) the graft copolymer is preferably b1:b2=80:20 to 20:80 (mass ratio), particularly preferably b1:b2=60:40 to 40:60.

[0022] The content of the (B) graft copolymer in the polyamide resin composition of this embodiment is 1 to 15 parts by mass, preferably 2 to 12 parts by mass, and more preferably 3 to 10 parts by mass, per 100 parts by mass of the (A) polyamide resin. When the content is equal to or greater than the lower limit, sliding properties are effectively exhibited, and when the content is equal to or less than the upper limit, wear resistance and mechanical properties are improved.

[0023] (C) Copper compound Examples of the copper compound (C) used in this embodiment include copper halides, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, copper salicylate, copper nicotinate, and copper stearate, as well as copper complex salts coordinated with chelating agents such as ethylenediamine and ethylenediaminetetraacetic acid. These copper compounds may be used alone or in combination. Among these, copper iodide, copper (I) bromide, copper (II) bromide, copper (I) chloride, and copper acetate are preferred, with copper iodide being more preferred. From the perspective of sliding properties, these copper compounds are preferably used in the form of a masterbatch with (D) a halide of a metal selected from the group consisting of alkali metals and alkaline earth metals.

[0024] The blending amount of (C) copper compound is 0.01 to 5 parts by mass, preferably 0.01 to 4 parts by mass, and more preferably 0.03 to 3 parts by mass, per 100 parts by mass of (A) polyamide resin. By adjusting the blending amount to this range, heat aging resistance is sufficiently improved, copper deposition and corrosion can be suppressed, and the effect of reducing the friction coefficient and wear depth is also exhibited.

[0025] (D) Halides of metals selected from the group consisting of alkali metals and alkaline earth metals Examples of (D) metal halides selected from the group consisting of alkali metals and alkaline earth metals (hereinafter sometimes abbreviated as "metal halides") used in this embodiment include potassium iodide, sodium iodide, potassium bromide, potassium chloride, and sodium chloride. Among these, potassium iodide is preferred. These metal halides may be used alone or in combination of two or more.

[0026] The blending amount of (D) metal halide is 0.05 to 5 parts by mass, preferably 0.1 to 4 parts by mass, and more preferably 0.2 to 3 parts by mass, per 100 parts by mass of (A) polyamide resin. By blending (D) metal halide in this range, heat aging resistance is sufficiently improved, copper deposition and corrosion can be suppressed, and the coefficient of friction and wear depth can also be effectively reduced.

[0027] The maximum particle size of the (C) copper compound and (D) metal halide to be added is preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. In the present invention, the particle diameter refers to the biaxial average diameter, i.e., the average value of the minor axis and the major axis. Here, the minor axis and the major axis refer to the short side and the long side, respectively, of the circumscribing rectangle that has the smallest circumscribing area of ​​the particle. The maximum particle diameter of (C) the copper compound and (D) the metal halide can be measured by observing at least 50 particles using a scanning electron microscope (SEM). By setting the maximum particle size within the above range, the (C) copper compound and (D) metal halide can be finely dispersed in the (A) polyamide resin even if the moisture content in the (A) polyamide resin is low, thereby further alleviating problems such as metal deposition and corrosion, and further improving the toughness, heat resistance, aging resistance, reduction in coefficient of friction and wear depth, appearance, and color tone of the resulting polyamide resin composition.

[0028] When the (C) copper compound and the (D) metal halide are prepared as a masterbatch, the molar ratio of halogen to copper (halogen / copper) in the masterbatch is preferably 3 to 30, more preferably 4 to 25, and even more preferably 5 to 23. A molar ratio of halogen to copper equal to or greater than the lower limit is preferred because copper deposition and metal corrosion can be suppressed, whereas a molar ratio of halogen to copper equal to or less than the upper limit can suppress corrosion of the molding machine screw and the like without impairing mechanical properties such as toughness.

[0029] In this embodiment, an organic compound (excluding polyamide) having at least one amide group can be present in the masterbatch. The presence of the organic compound having at least one amide group can prevent the (C) copper compound and (D) metal halide from dissolving in the water in the (A) polyamide resin and forming a complex during melt-kneading. This stabilizes the dispersion of the (C) copper compound and (D) metal halide in the (A) polyamide resin without adversely affecting the (A) polyamide resin, and prevents precipitation and deterioration.

[0030] The organic compound having at least one amide group used in this embodiment is a compound having at least one amide group in the molecular chain, and specific examples thereof include monoamides, substituted amides, methylol amides, and bisamides. Monoamides are represented by the general formula R-CONH2 (where R is a saturated aliphatic, unsaturated aliphatic, or aromatic group having 8 to 30 carbon atoms, or one in which some of the -H's have been replaced with -OH). Specific examples include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, oleic acid amide, erucic acid amide, linosyl acid amide, etc. Substituted amides are those of the general formula R 1 -CONH-R 2 (However, R 1 and R 2are each independently a saturated aliphatic, unsaturated aliphatic, or aromatic group having 8 to 30 carbon atoms, or an alkyl group in which some of the -H groups have been replaced with -OH.) Specific examples include N-lauryl lauric acid amide, N-paltimyl palmitic acid amide, N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide, N-stearyl 12-hydroxystearic acid amide, and N-oleyl 12-hydroxystearic acid amide. Methylolamides are represented by the general formula R-CONHCHOH (where R is a saturated aliphatic, unsaturated aliphatic, or aromatic group having 8 to 30 carbon atoms, or one in which some of the -H groups have been replaced with -OH). Specific examples include methylol stearamide and methylol behenamide. Bisamides are represented by the general formula (R-CONH)2(CH2)n (wherein R is a saturated aliphatic, unsaturated aliphatic, or aromatic group having 8 to 30 carbon atoms, or a group in which some of the -H's have been replaced with -OH, and n is 1 to 8). Specific examples include methylene bislauric amide, methylene bislauric amide, methylene bishydroxystearic amide, ethylene biscaprylic amide, ethylene bislauric amide, ethylene bisstearic amide, ethylene bisisostearic amide, ethylene bishydroxystearic amide, ethylene bisbehenic amide, hexamethylene bisstearic amide, hexamethylene bisbehenic amide, hexamethylene bishydroxystearic amide, ethylene bisbehenic amide, hexamethylene bis(isostearic amide), ... Examples of the hydroxystearic acid amide include N,N'-hydroxystearic acid amide, butylene bishydroxystearic acid amide, N,N'-distearyl adipate amide, N,N'-distearyl sebacate amide, methylene bisoleate amide, ethylene bisoleate amide, ethylene biserucate amide, hexamethylene bisoleate amide, N,N'-dioleyl adipate amide, N,N'-dioleyl sebacate amide, m-xylylene bisstearic acid amide, and N,N'-distearyl isophthalate amide. These organic compounds having at least one amide group may be used alone or in combination of two or more. Among these, bisamides are preferred.

[0031] The amount of the organic compound having at least one amide group is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5.0 parts by mass, and even more preferably 1.0 to 4.0 parts by mass, per 100 parts by mass of the polyamide resin (A). By adjusting the amount within this range, the dispersibility of the copper compound (C) and the metal halide (D) in the polyamide resin (A) is improved, heat aging resistance is improved, and the coefficient of friction and wear depth are reduced, and copper deposition and corrosion are more effectively suppressed.

[0032] The moisture content of the masterbatch can be, for example, 0.06 to 1.0 mass%, 0.10 to 0.25 mass%, or 0.05 to 0.2 mass% relative to the total mass of the masterbatch. The moisture in the masterbatch may be present as moisture bound to polyamide molecules, or may be moisture attached to the masterbatch surface, such as the surface of masterbatch pellets or masterbatch powder. By controlling the moisture content within this range, aggregation of (C) copper compounds and (D) metal halides can be suppressed. This effectively improves mechanical properties such as toughness and heat aging resistance, reduces the coefficient of friction and wear depth, and further suppresses copper precipitation and metal corrosion. The moisture content of the masterbatch can be adjusted by controlling the degree of vacuum in the extruder, the immersion time and length in the strand bath during cooling, or the amount of water spray.

[0033] The polyamide resin composition in this embodiment has a moisture content of preferably 0.01 to 1 mass %, more preferably 0.025 to 0.5 mass %, and even more preferably 0.04 to 0.25 mass %, relative to the total mass of the polyamide resin composition. The moisture in the polyamide resin composition may be present as moisture bound to polyamide molecules, or may be moisture attached to the surface of the polyamide resin composition, for example, the surface of pellets or powder. However, from the viewpoint of more significantly exhibiting the effects of the present invention, it is more preferable that the moisture be present as moisture bound to polyamide molecules. By keeping the moisture content within this range, it is possible to suppress the aggregation of (C) copper compounds and (D) metal halides, which leads to a high effect of improving mechanical properties such as toughness and heat aging resistance, and also makes it possible to reduce the coefficient of friction and wear depth, and further suppress copper deposition and metal corrosion. The moisture content of the polyamide resin composition can be adjusted by controlling the degree of vacuum in the extruder, the immersion time and immersion length in the strand bath during cooling, or the amount of water sprayed.

[0034] (Hindered phenolic heat stabilizer (hindered phenolic antioxidant)) It is preferable that a heat stabilizer be further added to the polyamide resin composition. The heat stabilizer is not particularly limited, but examples thereof include phenolic stabilizers such as hindered phenol compounds, phosphite stabilizers, hindered amine stabilizers, triazine stabilizers, and sulfur stabilizers, with hindered phenol compounds, which are phenolic stabilizers, being preferred. These heat stabilizers are also effective in reducing the coefficient of friction and wear depth.

[0035] The content of the hindered phenol-based heat stabilizer is preferably 0.01 to 5 parts by mass, and more preferably 0.015 to 3 parts by mass, relative to 100 parts by mass of the (A) polyamide resin.

[0036] (fiber filler) Examples of fibrous fillers include, but are not limited to, carbon fiber, glass fiber, calcium silicate fiber, potassium titanate fiber, aluminum borate fiber, wollastonite, and carbon nanotubes. Among these, carbon fiber is particularly preferable from the viewpoint of improving sliding properties, and further from the viewpoint of wear resistance and reduction of wear depth in sliding properties, and has the characteristic of being less likely to damage the mating material. For example, either polyacrylonitrile (PAN)-based carbon fiber or pitch-based carbon fiber can be used, with PAN-based carbon fiber being preferred from the viewpoint of mechanical properties. The above-mentioned fibrous fillers may be used alone or in combination of two or more.

[0037] The fibrous filler is preferably used from the viewpoint of sliding properties and mechanical properties, and is preferably used in an amount of 1 part by mass or more and 30 parts by mass or less, more preferably 3 parts by mass or more and 20 parts by mass or less, and even more preferably 5 parts by mass or more and 10 parts by mass or less, per 100 parts by mass of the (A) polyamide resin.

[0038] From the viewpoint of productivity, it is preferable to add short carbon fibers of about 3 mm to 10 mm by melt kneading in an extruder. In this case, it is preferable to add the carbon fibers from a side feeder from the viewpoint of preventing breakage of the carbon fibers.

[0039] From the viewpoint of affinity with polyamide resin, the carbon fiber is preferably coated with a urethane-based sizing agent, a maleic anhydride-based sizing agent, an acrylic-based sizing agent, or a polyamide-based sizing agent. From the viewpoint of physical properties and sliding properties, the carbon fiber preferably has a diameter of 5 μm or more and 10 μm or less.

[0040] (Moldability improver) If necessary, a moldability improver may be added to the polyamide resin composition within the range that does not impair the object of the present invention. The moldability improver is not particularly limited, but examples thereof include higher fatty acids, higher fatty acid metal salts, higher fatty acid esters, and higher fatty acid amides.

[0041] Examples of higher fatty acids include saturated or unsaturated, straight-chain or branched aliphatic monocarboxylic acids having 8 to 40 carbon atoms, such as stearic acid, palmitic acid, behenic acid, erucic acid, oleic acid, lauric acid, and montanic acid. Among these, stearic acid and montanic acid are preferred.

[0042] The higher fatty acid metal salt is a metal salt of the above higher fatty acid. As the metal element of the metal salt, elements of Groups 1, 2 and 3 of the periodic table, zinc, aluminum, etc. are preferred, and elements of Groups 1 and 2 such as calcium, sodium, potassium and magnesium, and aluminum, etc. are more preferred. Examples of metal salts of higher fatty acids include metal salts of stearic acid such as calcium stearate, aluminum stearate, zinc stearate, and magnesium stearate; metal salts of montanic acid such as calcium montanate and sodium montanate; and metal salts of palmitic acid such as calcium palmitate. Among these, metal salts of montanic acid and metal salts of stearic acid are preferred.

[0043] The higher fatty acid ester is an ester of the above higher fatty acid with an alcohol. Esters of aliphatic carboxylic acids having 8 to 40 carbon atoms and aliphatic alcohols having 8 to 40 carbon atoms are preferred. Examples of fatty alcohols include stearyl alcohol, behenyl alcohol, and lauryl alcohol. Examples of higher fatty acid esters include stearyl stearate and behenyl behenate.

[0044] The higher fatty acid amide is an amide compound of the above higher fatty acid. Examples of higher fatty acid amides include stearic acid amide, oleic acid amide, erucic acid amide, ethylene bisstearylamide, ethylene bisoleylamide, N-stearylstearylamide, and N-stearylerucic acid amide.

[0045] These higher fatty acids, higher fatty acid metal salts, higher fatty acid esters, and higher fatty acid amides may be used singly or in combination of two or more.

[0046] (coloring agent) If necessary, a colorant may be added to the polyamide resin composition within the range that does not impair the object of the present invention. The colorant is not particularly limited, but examples thereof include dyes such as nigrosine, pigments such as titanium oxide and carbon black, metal particles such as aluminum, colored aluminum, nickel, tin, copper, gold, silver, platinum, iron oxide, stainless steel, and titanium, and metallic pigments such as mica pearl pigments and colored graphite.

[0047] (Other resins) If necessary, other resins may be added to the polyamide resin composition within the scope of the present invention. Such resins are not particularly limited, but include thermoplastic resins and rubber components, which will be described later.

[0048] Examples of thermoplastic resins include polystyrene-based resins such as atactic polystyrene, isotactic polystyrene, syndiotactic polystyrene, AS (acrylonitrile-styrene) resin, and ABS (acrylonitrile-butadiene-styrene) resin; acrylic resins such as polyacrylic acid, polyacrylic acid ester, and polymethyl methacrylate; and halogen-containing vinyl compound-based resins such as polyvinyl chloride and polyvinylidene chloride. These thermoplastic resins may be used singly or in combination of two or more.

[0049] Examples of rubber components include natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, polysulfide rubber, thiokol rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber, styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), styrene-butadiene random copolymer, hydrogenated styrene-butadiene random copolymer, styrene-ethylene-propylene random copolymer, Examples of such rubbers include styrene-ethylene-butylene random copolymers, ethylene-propylene copolymers (EPR), ethylene-(1-butene) copolymers, ethylene-(1-hexene) copolymers, ethylene-(1-octene) copolymers, ethylene-propylene-diene copolymers (EPDM), and core-shell types such as butadiene-acrylonitrile-styrene-core-shell rubber (ABS), methyl methacrylate-butadiene-styrene-core-shell rubber (MBS), methyl methacrylate-butyl acrylate-styrene-core-shell rubber (MAS), octyl acrylate-butadiene-styrene-core-shell rubber (MABS), alkyl acrylate-butadiene-acrylonitrile-styrene-core-shell rubber (AABS), butadiene-styrene-core-shell rubber (SBR), and siloxane-containing core-shell rubbers such as methyl methacrylate-butyl acrylate siloxane. These rubber components may be used singly or in combination of two or more.

[0050] (Perfluorooctanoic acid and its salts) In the polyamide resin composition of the present embodiment, the content of perfluorooctanoic acid and its salts is preferably less than 10 ppb by mass relative to the total mass of the polyamide resin composition. By ensuring that the content is within this range, the temperature during melt-kneading can be kept low, and the mechanical strength of the polyamide resin tends to be increased.

[0051] (Method of producing polyamide resin composition) The polyamide resin composition of the present embodiment can be obtained by mixing and kneading (A) a polyamide resin, (B) a graft copolymer, (C) a copper compound, and (D) a metal halide, together with other components that are blended as necessary.

[0052] The (C) copper compound and (D) metal halide are preferably prepared as a masterbatch in advance and then melt-kneaded with the (A) polyamide resin and the (B) graft copolymer, or alternatively, the (C) copper compound, (D) metal halide, and a portion of the (A) polyamide resin are preferably prepared as a masterbatch in advance and then melt-kneaded with the remainder of the (A) polyamide resin and the (B) graft copolymer.

[0053] (Masterbatch preparation process) The masterbatch is prepared by melt-kneading the (C) copper compound and (D) metal halide. In addition to the (C) copper compound and (D) metal halide, it is preferable to blend the organic compound having at least one amide group (excluding polyamide). In addition to the organic compound having at least one amide group, it is preferable to blend (A) a polyamide resin.

[0054] When the organic compound having at least one amide group is blended with the (A) polyamide resin, the (C) copper compound, the (D) metal halide, and the organic compound having at least one amide group may each be blended individually with the (A) polyamide resin, or at least two of the three compounds may be premixed and then blended with the (A) polyamide resin, or at least two of the three compounds may be premixed and pulverized and then blended with the (A) polyamide resin, or at least two of the three compounds may be premixed and pulverized to form tablets and then blended with the (A) polyamide resin.

[0055] The compounds can be mixed by any known method, such as a method using a tumbler, a Henschel mixer, a Plosser mixer, a Nauta mixer, a flow jet mixer, or the like. The compound can be pulverized by any known method, such as pulverization using a hammer mill, knife mill, ball mill, jaw crusher, cone crusher, roller mill, jet mill, or mortar. The compound can be made into tablets by known methods such as compression granulation, tableting, dry extrusion granulation, and melt extrusion granulation.

[0056] The melt-kneading device is not particularly limited, and known devices can be used. For example, melt-kneaders such as single-screw or twin-screw extruders, Banbury mixers, and mixing rolls are preferably used. Of these, twin-screw extruders are preferably used. The melt-kneader may also be equipped with a degassing mechanism (vent) and a side feeder.

[0057] The melt-kneading temperature in this embodiment is preferably a temperature about 1 to 100°C higher than the melting point or softening point of the (A) polyamide resin determined by differential scanning calorimetry (DSC) measurement in accordance with JIS K7121. The shear rate in the kneader is 100 (SEC -1 ) or more, and the average residence time during kneading is preferably about 1 to 15 minutes.

[0058] (Melting and kneading process of masterbatch, (A) polyamide resin, and (B) graft copolymer) The polyamide resin composition of this embodiment is prepared by melt-kneading the masterbatch, the polyamide resin (A), and the graft copolymer (B). When the masterbatch contains a portion of the polyamide resin (A), the polyamide resin composition of this embodiment is prepared by melt-kneading the remaining portion of the polyamide resin (A) and the graft copolymer (B) with the masterbatch. The (C) copper compound and (D) metal halide are preferably blended so that the total mass of them is 0.1 to 100 parts by mass, more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the (A) polyamide resin. Blending within this range inhibits metallic copper deposition and metal corrosion in extruders and molding machines, thereby improving stability during processing. In addition, without deteriorating the mechanical properties of the product, it is possible to further improve heat aging resistance, further reduce the coefficient of friction and wear depth, and further suppress changes in appearance color due to water absorption. The amount of the graft copolymer (B) blended relative to 100 parts by mass of the polyamide resin (A) is as described above.

[0059] The masterbatch, (A) the polyamide resin, and (B) the graft copolymer are melt-kneaded together with other components that are blended as needed. The melt-kneading step is preferably carried out using various commonly used extruders such as a single-screw or twin-screw extruder, and is particularly preferably carried out using a twin-screw extruder from the viewpoints of productivity, versatility, etc. In this case, the melt-kneading temperature, which depends on the type of (A) polyamide resin, is preferably adjusted so that the temperature of the molten resin discharged from the extruder outlet is equal to or higher than the melting points of the (A) polyamide resin and the (B) graft copolymer. By setting the melt-kneading temperature within the above range, poor extrusion kneading is unlikely to occur, and fine dispersion of the (B) graft copolymer is possible.

[0060] In the case of a twin-screw extruder, it is preferable that the extruder screw has a kneading zone that combines at least two kneading disks. The kneading zone is a region that applies high shear to the molten resin while suppressing its advance in the extrusion direction so that kneading is carried out effectively. The melt-kneading step is preferably carried out by supplying (A) polyamide resin, (B) graft copolymer and masterbatch (containing (C) copper compound and (D) metal halide, and optionally (A) polyamide resin) and optionally other components (such as hindered phenol-based heat stabilizer) from the most upstream supply port of a twin-screw extruder, melt-kneading them in a first kneading zone to obtain a first molten kneaded product, supplying a fibrous filler from a side supply port provided downstream of the first kneading zone, if necessary, and dispersing the unmelted fibrous filler in the first molten kneaded product in a second kneading zone provided downstream of the side supply port.

[0061] It is desirable to set the various conditions of the extruder (barrel temperature, screw rotation speed, discharge rate, etc.) so that the resin temperature of the polyamide resin composition discharged from the extruder outlet after the melt-kneading step is higher than the crystallization temperature of the (A) polyamide resin, 280° C. or higher. By setting the temperature of the polyamide resin composition at the discharge outlet to 280° C. or higher, the (A) polyamide resin and the (B) graft copolymer can be more finely dispersed, resulting in excellent sliding properties and mechanical properties.

[0062] The temperature of the polyamide resin composition is preferably measured, for example, by directly contacting the detection part of a commercially available thermocouple thermometer with the molten polyamide resin composition discharged from the outlet of the extruder. The temperature of the extruder for achieving the above temperature of the polyamide resin composition is preferably set to 280°C or higher.

[0063] By molding the polyamide resin composition, a molded article of the polyamide resin composition of the present embodiment can be obtained. The method for obtaining the molded body is not particularly limited, and any known molding method can be used. Examples of molding methods include extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decorative molding, other material molding, gas-assisted injection molding, foam injection molding, low-pressure molding, ultra-thin-wall injection molding (ultra-high-speed injection molding), and in-mold composite molding (insert molding, outsert molding).

[0064] The temperature setting of the molding machine when molding the polyamide resin composition of this embodiment is preferably in the range of from 5° C. higher than the melting point of the (A) polyamide resin used to 310° C., more preferably from 10° C. higher to 300° C., and even more preferably from 15° C. higher to 295° C. Setting the temperature of the molding machine within this temperature range allows for more effective kneading of the polyamide resin composition during molding, and allows for more sufficient dispersion of the (B) graft copolymer and the like in the polyamide resin composition.

[0065] The polyamide resin composition of the present embodiment has excellent sliding properties and an excellent balance of mechanical properties such as toughness and impact resistance, and therefore can be used in a variety of sliding applications. For example, examples of sliding members include bearings, gears, thrust washers, seal rings, etc., and the material can be suitably used for these. [Example]

[0066] The present invention will be described in detail below with reference to specific examples and comparative examples, but the present invention is not limited to the following examples. The raw materials and measurement methods for physical property tests used in the examples and comparative examples are as follows.

[0067] [Raw materials] (A) Polyamide resin (Production Example 1) Preparation of Polyamide 66 15,000 g of an equimolar salt of adipic acid and hexamethylenediamine, along with 0.5 mol% excess adipic acid relative to the total equimolar salt components, were dissolved in 15,000 g of distilled water to obtain a 50% by mass aqueous solution of the raw material monomer. The resulting aqueous solution was placed in a 40 L autoclave, and the autoclave was purged with nitrogen. The aqueous solution was concentrated to a solution concentration of 70% by mass by gradually removing steam while stirring at a temperature of 110 to 150°C. The internal temperature was then raised to 220°C. At this time, the autoclave was pressurized to 1.8 MPa. The reaction was continued for 1 hour while gradually removing steam to maintain the pressure at 1.8 MPa until the internal temperature reached 270°C. The pressure was then reduced to atmospheric pressure over approximately 1 hour. After atmospheric pressure was reached, the mixture was discharged in the form of strands from the lower nozzle, cooled with water, and cut into pellets. The pellets were dried in a nitrogen stream at 90°C for 4 hours. The relative viscosity of the pellets in 98% sulfuric acid was 2.71, the melting point was 265°C, and the crystallization temperature was 220°C.

[0068] (B) Graft copolymer ((b1) main chain: olefin copolymer, (b2) side chain: vinyl copolymer) (B)-1 (graft copolymer-1): MODIPERA A1401, manufactured by NOF Corporation, melting point 111°C, (b1):(b2) = 50:50 (B)-2 (graft copolymer-1): MODIPERA A1100, manufactured by NOF Corporation, melting point 110°C, (b1):(b2) = 70:30 When the above graft copolymer was measured by the following measurement method, it was found to contain no perfluorooctanoic acid or its salts, or PFOA-related substances.

[0069] (C) Copper compound Copper iodide: Copper(I) iodide, manufactured by Wako Pure Chemical Industries, Ltd. (D) Metal halides Potassium iodide: Potassium iodide, manufactured by Wako Pure Chemical Industries, Ltd.

[0070] (Production Example 2) Preparation of Masterbatch To 100 parts by weight of the (A) polyamide resin obtained in (Production Example 1), 1.5 parts by weight of the (C) copper compound and 32.5 parts by weight of a 40% by weight aqueous solution of the (D) metal halide were added, and the mixture was melt-kneaded using a twin-screw extruder (manufactured by the Plastics Engineering Research Institute, twin-screw co-rotating type, L / D=60 (D=30φ)) at a screw rotation speed of 100 rpm and a cylinder temperature of 280°C to obtain a masterbatch containing the (A) polyamide resin, the (C) copper compound, and the (D) metal halide. This master batch was used in Examples 1, 3 to 6, 8 to 12, and 14.

[0071] Polytetrafluoroethylene (PTFT) powder (used in Comparative Example 5) It contained perfluorooctanoic acid and its salts, as well as PFOA-related substances. Fluorine-based resin - polytetrafluoroethylene: TLP10F-1, manufactured by Mitsui DuPont Fluorochemicals, number average primary particle size 0.2 μm, melting point 329°C

[0072] Fibrous filler: Carbon fiber: Teijin Ltd., HTC413 Hindered phenolic heat stabilizer (hindered phenolic antioxidant): BASF, IRGANOX 1098 Spreader: Sanyo Chemical Industries, Ltd., PEG400

[0073] [Forming method] The polyamide resin composition pellets obtained in the examples and comparative examples were molded into multipurpose test specimens of type A in accordance with ISO 3167 using an injection molding machine PS-40E (manufactured by Nissei Plastics Co., Ltd.) with an injection and dwell time of 25 seconds, a cooling time of 15 seconds, a mold temperature of 80°C, and a cylinder temperature of (melting point of polyamide resin + 30)°C.

[0074] Furthermore, pellets of the compositions obtained in the examples and comparative examples were used in the injection molding machine to prepare hollow cylindrical test pieces with an outer diameter of 25.7 mm, an inner diameter of 20 mm, and a height of 17 mm, with the injection and pressure holding time set to 25 seconds, the cooling time set to 15 seconds, the mold temperature set to 80°C, and the cylinder temperature set to (melting point of polyamide resin + 30)°C, to obtain test pieces for evaluating sliding properties.

[0075] [Measurement method] <Moisture content of polyamide resin composition> The moisture content was measured by coulometric titration (Karl Fischer method) using a moisture vaporizer (VA-06 model, manufactured by Mitsubishi Chemical Corporation) with 0.7 g of the polyamide resin composition.

[0076] <Relative viscosity of sulfuric acid> The sulfuric acid relative viscosity ηr of the polyamide resin at 25°C was measured in accordance with JIS-K 6920. Specifically, a 1% concentration solution (ratio: (1 g of polyamide) / (100 mL of 98% sulfuric acid)) was prepared using 98% sulfuric acid, and the sulfuric acid relative viscosity ηr was measured using the obtained solution at a temperature of 25°C.

[0077] <Evaluation of sliding characteristics> <Friction coefficient, wear depth> A reciprocating friction and wear test was conducted using a reciprocating friction and wear tester (Model AFT-15MS, manufactured by Toyo Seimitsu Co., Ltd.) and a SUS304 test piece (a sphere with a diameter of 5 mm) as the counter material at a linear velocity of 50 mm / sec, a reciprocating distance of 20 mm, a temperature of 23°C, and a humidity of 50%. A friction coefficient test was also conducted with a load of 4 kg and 10,000 reciprocating strokes. The wear depth at the center of the wear mark on the sample after the sliding test was measured using a surface roughness tester (Model 575A-30, manufactured by Toyo Seimitsu Co., Ltd.).

[0078] <Wear mark evaluation> Using a digital microscope (Keyence VHX-5000 model) at a magnification of 20x, the appearance of the wear marks after the reciprocating sliding test was evaluated on a scale of 1 to 5 based on the table below, with reference to the reference example shown in Figure 1.

[0079] [Table 1]

[0080] <Tensile test> The compositions obtained in the examples and comparative examples were molded under the conditions shown in [Molding method] into A-type test pieces, and a tensile test was carried out in accordance with ISO 527 at a test speed of 50 mm / min to measure the tensile strength. The ratio of the displacement of the chuck distance at break to the chuck distance before the test was taken as the tensile elongation (%). Tensile elongation (%) = 100 x breaking point displacement (mm) / initial chuck distance (mm) The tensile strength was divided by the tensile elongation to obtain the tensile modulus. Tensile modulus = tensile strength / tensile elongation

[0081] <Bending test> The compositions obtained in the examples and comparative examples were molded under the conditions shown in [Molding method] to obtain A-type test pieces, which were processed into 80 × 10 × 4 mm, and their bending strength was measured at a test speed of 2 mm / min in accordance with ISO 178. Next, the flexural modulus was calculated from the stress gradient in the specified strain range (0.05% to 0.25%) according to the secant method.

[0082] <Charpy impact strength> The compositions obtained in the examples and comparative examples were molded under the conditions shown in [Molding method] to prepare A-type test pieces of 80 x 10 x 4 mm, and the notched Charpy impact strength (kJ / m 2 ) was measured.

[0083] <Method for measuring the concentration of perfluorooctanoic acid (PFOA) and its salts> The concentrations of perfluorooctanoic acid and its salts in the compositions prepared in the examples and comparative examples were measured in accordance with CEN / TS 15968.

[0084] Example 1 (A) Polyamide resin (98 parts by mass), graft copolymer (B)-1 (5 parts by mass), the masterbatch ((A) polyamide resin (2 parts by mass), (C) copper compound (0.03 parts by mass), and (D) metal halide (0.26 parts by mass) obtained in Production Example 2, a hindered phenol-based heat stabilizer (0.03 parts by mass), and a spreading agent (0.02 parts by mass) were mixed and fed into the most upstream feed port of a twin-screw extruder (manufactured by Coperion Co., Ltd., trade name "ZSK26MC") with a screw diameter of 26 mm. The barrel temperature of the extruder was then set to 290°C, and the mixture was extruded while melt-kneading at a screw rotation speed of 300 rpm to obtain pellets of a polyamide resin composition. Using the obtained pellets of the polyamide resin composition, test pieces were prepared by the method described in [Molding method], and evaluations were carried out by the methods described in [Measurement method].

[0085] Example 2 Pellets of a polyamide resin composition containing each component in the blending amounts shown in Table 2 below were obtained in the same manner as in Example 1, except that (A) polyamide resin, (C) copper compound, and (D) metal halide were added as powders instead of being prepared as masterbatches, and evaluation was carried out.

[0086] Example 3 Pellets of a polyamide resin composition were obtained in the same manner as in Example 1, except that no hindered phenol-based heat stabilizer was added, and evaluation was carried out.

[0087] (Examples 4 and 5) Pellets of the polyamide resin composition were obtained in the same manner as in Example 1, except that the amount of the graft copolymer (B)-1 was increased as shown in Table 2 below, and evaluation was carried out.

[0088] Example 6 Pellets of a polyamide resin composition were obtained in the same manner as in Example 1, except that graft copolymer (B)-2 was blended in place of graft copolymer (B)-1, and evaluation was carried out.

[0089] Example 7 Pellets of a polyamide resin composition containing each component in the amounts shown in Table 3 below were obtained in the same manner as in Example 6, except that (A) polyamide resin, (C) copper compound, and (D) metal halide were not prepared as masterbatches but were added as powders, and evaluation was carried out.

[0090] Example 8 Pellets of a polyamide resin composition were obtained in the same manner as in Example 6, except that no hindered phenol-based heat stabilizer was added, and evaluation was carried out.

[0091] (Examples 9 and 10) Pellets of the polyamide resin composition were obtained in the same manner as in Example 6, except that the amount of the graft copolymer (B)-2 was increased as shown in Table 3 below, and evaluation was carried out.

[0092] Example 11 (A) Polyamide resin (98 parts by mass), graft copolymer (B)-1 (5 parts by mass), the masterbatch ((A) polyamide resin (2 parts by mass), (C) copper compound (0.03 parts by mass), (D) metal halide (0.26 parts by mass)), hindered phenol-based heat stabilizer (0.03 parts by mass), and spreading agent (0.02 parts by mass) were mixed. The resulting mixture was fed into the most upstream feed port of a twin-screw extruder ("ZSK26" manufactured by Coperion). The barrel temperature of the extruder was set to 290°C, and the mixture was melt-kneaded at a screw rotation speed of 300 rpm. Carbon fiber (10 parts by mass) was then fed as a fibrous filler through a feed port located downstream of the most upstream feed port. The mixture was then discharged from multiple 3 mm diameter extruder nozzles, water-cooled, and pelletized to obtain pellets of the polyamide resin composition approximately 3 mm long and 3 mm in diameter. The temperature at the extruder outlet was 290° C., and the extrusion rate was 25 kg / hr. The obtained pellets were dried at 80° C. for 12 hours, and then test pieces were prepared by the method described in the above [Molding method] and evaluated.

[0093] Example 12 Pellets of a polyamide resin composition were obtained in the same manner as in Example 11, except that graft copolymer (B)-2 was blended in place of graft copolymer (B)-1, and evaluation was carried out.

[0094] Example 13 Pellets of a polyamide resin composition containing each component in the amounts shown in Table 4 below were obtained in the same manner as in Example 11, except that (A) polyamide resin, (C) copper compound, and (D) metal halide were added as powders rather than as masterbatches, and evaluation was carried out.

[0095] Example 14 Pellets of a polyamide resin composition were obtained in the same manner as in Example 11, except that no hindered phenol-based heat stabilizer was added, and evaluation was carried out.

[0096] Example 15 Pellets of a polyamide resin composition were obtained in the same manner as in Example 14, except that the amount of carbon fiber supplied as a fibrous filler was increased as shown in Table 4 below, and evaluation was carried out.

[0097] Example 16 The masterbatch used was obtained by the method described below. ((C) Nylon 66 masterbatch containing copper compound and (D) metal halide) 100 parts by weight of the polyamide resin (A) obtained in (Production Example 1) was premixed with 1.5 parts by weight of the copper compound (C) and 32.5 parts by weight of a 40% by weight aqueous solution of a metal halide (D), and then the mixture was melt-kneaded in a TEX30 twin-screw extruder (L / D: 45.5) manufactured by The Japan Steel Works, Ltd. at a cylinder temperature of 275°C and a screw rotation speed of 150 rpm, and pelletized with a strand cutter. The mixture was then vacuum dried at 80°C for 8 hours to produce masterbatch pellets. (A) Polyamide resin (98 parts by mass), the above-mentioned masterbatch ((A) polyamide resin (2 parts by mass), (C) copper compound (0.03 parts by mass), and (D) metal halide (0.26 parts by mass)), graft copolymer (B)-2 (5 parts by mass), hindered phenol-based heat stabilizer (0.03 parts by mass), and spreading agent (0.02 parts by mass) were mixed and fed into the most upstream feed port of a twin-screw extruder (manufactured by Coperion Co., Ltd., trade name "ZSK26MC") with a screw diameter of 26 mm. The barrel temperature of the extruder was then set to 290°C, and the mixture was extruded while melt-kneading at a screw rotation speed of 300 rpm to obtain pellets of a polyamide resin composition. Using the obtained pellets of the polyamide resin composition, test pieces were prepared by the method described in [Molding method], and evaluations were carried out by the methods described in [Measurement method].

[0098] (Comparative Example 1) Pellets of a polyamide resin composition were obtained in the same manner as in Example 1, except that the hindered phenol-based heat stabilizer, (C) the copper compound, and (D) the metal halide were not blended, and evaluation was carried out.

[0099] (Comparative Example 2) Pellets of a polyamide resin composition were obtained in the same manner as in Example 6, except that the hindered phenol-based heat stabilizer, (C) the copper compound, and (D) the metal halide were not blended, and evaluation was carried out.

[0100] (Comparative Example 3) Pellets of a polyamide resin composition were obtained in the same manner as in Example 11, except that the hindered phenol-based heat stabilizer, (C) the copper compound, and (D) the metal halide were not blended, and evaluation was carried out.

[0101] Comparative Example 4 Test pieces were prepared using the polyamide resin (A) obtained in (Production Example 1) according to the method described in [Molding method], and evaluations were carried out.

[0102] (Comparative Example 5) Using a twin-screw extruder (manufactured by Coperion Co., Ltd., trade name "ZSK26MC") with a screw diameter of 26 mm, a mixture of (A) polyamide resin impregnated with (C) copper compound and (D) metal halide was fed from the most upstream feed port according to the formulation shown in Table 5, and polytetrafluoroethylene powder was fed from a side feed port provided downstream of the most upstream feed port. The extrusion conditions were 280°C up to the melting zone, 270°C from the melting zone onwards, and a screw rotation speed of 300 rpm, to perform melt kneading, thereby obtaining pellets of the polyamide resin composition. The side feed port for adding the polytetrafluoroethylene powder was set at the seventh barrel from the upstream of the 12 barrels. Using the obtained pellets of the polyamide resin composition, test pieces were prepared by the method described in [Molding method], and each test piece was evaluated.

[0103] (Comparative Example 6) The masterbatch used was obtained by the method described below. (C) Nylon 66 masterbatch containing copper compounds and (D) metal halides 100 parts by mass of the polyamide resin (A) obtained in (Production Example 1) was premixed with 1.5 parts by mass of the copper compound (C) and 32.5 parts by mass of a 40% by mass aqueous solution of a metal halide (D), and then the mixture was melt-kneaded in a TEX30 twin-screw extruder (L / D: 45.5) manufactured by The Japan Steel Works, Ltd. at a cylinder temperature of 275°C and a screw rotation speed of 150 rpm, and pelletized with a strand cutter. The mixture was then vacuum dried at 80°C for 8 hours to produce masterbatch pellets. (A) Polyamide resin (98 parts by mass), masterbatch ((A) polyamide resin (2 parts by mass), (C) copper compound (0.03 parts by mass), and (D) metal halide (0.26 parts by mass)), and spreading agent (0.02 parts by mass) were mixed and fed into the most upstream feed port of a twin-screw extruder (manufactured by Coperion Co., Ltd., trade name "ZSK26MC") with a screw diameter of 26 mm. The barrel temperature of the extruder was then set to 290°C, and the mixture was extruded while melt-kneading at a screw rotation speed of 300 rpm to obtain pellets of a polyamide resin composition. Using the obtained pellets of the polyamide resin composition, test pieces were prepared by the method described in [Molding method], and evaluations were carried out by the methods described in [Measurement method].

[0104] [Table 2]

[0105] [Table 3]

[0106] [Table 4]

[0107] [Table 5]

[0108] [Table 6]

[0109] [Table 7]

[0110] [Table 8]

[0111] [Table 9]

[0112] As is clear from the results of the Examples in Tables 6 to 8, the polyamide resin composition of the present invention had an excellent balance of sliding properties (friction coefficient, wear depth, wear marks, standard deviation of friction coefficient and wear depth), toughness, and impact resistance. On the other hand, as is clear from the results of Comparative Examples 1 to 3 in Table 9, the polyamide resin compositions different from the present invention have excellent sliding properties compared to Comparative Example 4, as in the Examples, but are inferior to the present invention in particular in sliding properties. Furthermore, only Comparative Example 5, which used PTFE, had PFOA and its salts of 10 ppb by mass or more. In the other Examples and Comparative Examples, PFOA and its salts were less than 10 ppb by mass (detection limit). [Industrial Applicability]

[0113] The polyamide resin composition of the present invention has excellent sliding properties and mechanical properties, and therefore has potential applications in the fields of automobiles, electrical and electronics, machinery and industry, office equipment, aviation and space, etc.

Claims

1. (A) a polyamide resin, (B) a graft copolymer in which a side chain containing polystyrene or acrylonitrile is grafted onto a main chain containing polyethylene; (C) a copper compound, and (D) a halide of a metal selected from the group consisting of alkali metals and alkaline earth metals; Relative to 100 parts by mass of the (A) polyamide resin, the content of the graft copolymer (B) is 1 to 15 parts by mass, the content of the (C) copper compound is 0.01 to 5 parts by mass, The polyamide resin composition contains 0.05 to 5 parts by mass of the (D) halide of a metal selected from the group consisting of alkali metals and alkaline earth metals.

2. 2. The polyamide resin composition according to claim 1, further comprising 0.01 to 5 parts by mass of a hindered phenol-based heat stabilizer per 100 parts by mass of the polyamide resin (A).

3. 3. The polyamide resin composition according to claim 1, further comprising 1 to 30 parts by mass of a fibrous filler per 100 parts by mass of the polyamide resin (A).

4. The polyamide resin composition according to any one of claims 1 to 3, which does not contain perfluorooctanoic acid and its salts at 10 ppb by mass or more.

5. (C) preparing a masterbatch containing a copper compound and (D) a halide of a metal selected from the group consisting of alkali metals and alkaline earth metals; and a step of melt-kneading the masterbatch, (A) the polyamide resin, and (B) the graft copolymer; A method for producing the polyamide resin composition according to any one of claims 1 to 4, comprising:

6. The method for producing a polyamide resin composition according to claim 5, wherein the melt-kneading temperature is 280°C or higher.

Images