Polyamide resin composition

Abstract

Provided is a polyamide resin composition having satisfactory mechanical properties including tensile properties, flexural properties and impact resistance and having a low water absorption rate.　The polyamide resin composition according to the present invention comprises 55 to 78% by mass of an aliphatic polyamide resin (A), 20 to 35% by mass of glass fibers (B), 1 to 9% by mass of a crosslinking agent (C), 0.1 to 1.5% by mass of a heat-resisting agent (D), and 0 to 6% by mass of an inorganic filler (E) that is different from glass fibers in 100% by mass of the polyamide resin composition, in which the aliphatic polyamide resin (A) has an average number of carbon atoms of more than 6 per one amide group.

Description

Polyamide resin composition

[0001] The present invention relates to a polyamide resin composition.

[0002] Polyamide resins have excellent mechanical properties, heat resistance, and chemical resistance, and are therefore widely used as engineering plastics in automobile parts, machine parts, sliding parts, electric and electronic parts, and the like.

[0003] In order to improve the sliding properties and strength when used for these applications, polyamide resin compositions in which a crosslinking agent is blended with a polyamide resin are known (see, for example, Patent Documents 1 and 2). In Patent Documents 1 and 2, polyamide 46, polyamide 66, polyamide 6, polyamide 9T, polyamide 6 / 11, etc. are used as the polyamide resin. In Patent Documents 1 and 2, the polyamide resin composition is irradiated with active energy rays to crosslink the crosslinking agent, thereby improving the sliding properties and strength.

[0004] On the other hand, Patent Document 3 discloses a polyamide resin composition that contains a crosslinking agent but has improved creep properties without being directly irradiated with active energy rays.

[0005] Japanese Patent Publication No. 2015-209512 Japanese Patent Publication No. 6283453 Japanese Patent Publication No. 2003-327634

[0006] In Patent Documents 1 and 2, the resin used as the polyamide resin has a high melting point, which causes problems with moldability when producing a molded article. In Patent Document 3, there is still room for improvement in mechanical properties. Therefore, an object of the present invention is to provide a polyamide resin composition that has good mechanical properties such as tensile properties, flexural properties, and impact resistance, low water absorption, and not too high density.

[0007] The present invention relates to the following items [1] to [8]: [1] A polyamide resin composition comprising, based on 100% by mass of the polyamide resin composition, 55 to 78% by mass of an aliphatic polyamide resin (A), 20 to 35% by mass of a glass fiber (B), 1 to 9% by mass of a crosslinking agent (C), 0.1 to 1.5% by mass of a heat stabilizer (D), and 0 to 6% by mass of an inorganic filler other than glass fiber (E), wherein the aliphatic polyamide resin (A) has an average number of carbon atoms per amide group of more than 6. [2] The polyamide resin composition of [1], wherein the aliphatic polyamide resin (A) has a melting point of 170 to 210°C as measured in accordance with ISO 11357-3. [3] The polyamide resin composition of [1] or [2], wherein the aliphatic polyamide resin (A) is at least one selected from the group consisting of at least one homopolymer selected from the group consisting of polynonamethylene dodecamide (polyamide 912), polydecamethylene sebacamide (polyamide 1010), polydecamethylene dodecamide (polyamide 1012), polydodecamethylene dodecamide (polyamide 1212), polyundecane amide (polyamide 11), and polydodecanamide (polyamide 12), and at least one copolymer selected from the group consisting of polyamide 6 / 12 copolymer and polyamide 6 / 6 / 12 copolymer. [4] The polyamide resin composition of any one of [1] to [3], wherein the crosslinking agent (C) is at least one selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, trimethallyl isocyanurate, diallyl phthalate, and diallyl benzene phosphonate. [5] The polyamide resin composition of any one of [1] to [4], wherein the heat-resistant agent (D) is an inorganic heat-resistant agent. [6] The polyamide resin composition of any one of [1] to [5], wherein the glass fiber (B) is surface-treated with a surface treatment agent and / or a binder. [7] A molded product of the polyamide resin composition of any one of [1] to [6]. [8] A crosslinked polyamide resin composition obtained by irradiating a molded product of the polyamide resin composition of [7] with active energy rays. [9] The crosslinked polyamide resin composition of [8], having a density of 1.20 to 1.28 g / ml.

[0008] The polyamide resin composition of the present invention has good mechanical properties such as tensile properties, flexural properties and impact resistance, low water absorption and not too high density.

[0009] The polyamide resin composition of the present invention contains, based on 100% by mass of the polyamide resin composition, 55 to 78% by mass of an aliphatic polyamide resin (A), 20 to 35% by mass of a glass fiber (B), 1 to 9% by mass of a crosslinking agent (C), 0.1 to 1.5% by mass of a heat-resistant agent (D), and 0 to 6% by mass of an inorganic filler other than glass fiber (E), wherein the aliphatic polyamide resin (A) has an average number of carbon atoms per amide group of more than 6. The above contents are values ​​rounded to one digit.

[0010] <Aliphatic Polyamide Resin (A)> The polyamide resin composition contains an aliphatic polyamide resin (A). The aliphatic polyamide resin (A) has an average number of carbon atoms per amide group of more than 6.

[0011] Aliphatic polyamide resins include aliphatic homopolyamide resins and aliphatic copolyamide resins. Aliphatic homopolyamide resins are polyamide resins composed of one type of structural unit derived from an aliphatic monomer. Aliphatic homopolyamide resins may be composed of at least one type of lactam and an aminocarboxylic acid, which is a hydrolyzate of the lactam, or may be composed of a combination of one type of diamine and one type of dicarboxylic acid. Aliphatic copolyamide resins are polyamide resins composed of two or more structural units derived from aliphatic monomers. Aliphatic copolyamide resins are copolymers of two or more types selected from the group consisting of a combination of a diamine and a dicarboxylic acid, and a lactam and an aminocarboxylic acid. Here, a combination of a diamine and a dicarboxylic acid is considered to be one type of monomer, with one type of diamine and one type of dicarboxylic acid being the combination.

[0012] Specific preferred examples of the aliphatic polyamide resin (A) include aliphatic homopolyamides having an average number of carbon atoms per amide group of more than 6; aliphatic polyamide copolymers using only raw material monomers (constituent repeating units) that form aliphatic polyamides having an average number of carbon atoms per amide group of more than 6; and aliphatic polyamide copolymers having an average number of carbon atoms per amide group of more than 6 as the entire polyamide resin, which contain at least one raw material monomer (constituent repeating unit) that forms an aliphatic polyamide having an average number of carbon atoms per amide group of more than 6, and at least one raw material monomer (constituent repeating unit) that forms an aliphatic polyamide having an average number of carbon atoms per amide group of 6 or less.

[0013] An aliphatic homopolyamide resin having an average number of carbon atoms per amide group greater than 6 means that, when the structural units of the polyamide are derived from lactam and aminocarboxylic acid, the total number of carbon atoms contained in the structural units exceeds 6. When the structural units are derived from a combination of diamine and dicarboxylic acid, the sum of the total number of carbon atoms contained in the diamine and the total number of carbon atoms contained in the dicarboxylic acid, divided by 2, exceeds 6. In other words, the average number of carbon atoms includes the number of carbon atoms in the amide group.

[0014] An aliphatic copolyamide resin having an average number of carbon atoms per amide group of more than 6 means that the average number of carbon atoms in the copolymer is greater than 6, calculated by determining the number of carbon atoms per amide group in each structural unit constituting the copolymer as described above, and multiplying the molar concentration of each structural unit in the copolymer by the number of carbon atoms per amide group in each structural unit.

[0015] From the viewpoint of moldability and mechanical properties, the aliphatic polyamide resin (A) has an average of more than 6 carbon atoms per amide group, preferably 7 to 12 carbon atoms, and more preferably 10 to 12 carbon atoms.

[0016] From the viewpoint of moldability and mechanical properties, the melting point of the aliphatic polyamide resin (A) is preferably 170 to 210° C., more preferably 175 to 200° C. The melting point was measured in accordance with ISO 11357-3 using a differential scanning calorimeter by heating a sample to a temperature equal to or higher than the expected melting point, then lowering the temperature of the sample at a rate of 10° C. per minute to 30° C., leaving the sample as it is for about 1 minute, and then raising the temperature at a rate of 20° C. per minute. The melting point was determined as the peak temperature of the melting curve.

[0017] The terminal amino group concentration of the aliphatic polyamide resin (A), as determined by dissolving the resin in a mixed solvent of phenol and methanol and subjecting it to neutralization titration, is preferably in the range of 20 μmol / g or more, more preferably in the range of 20 μmol / g to 60 μmol / g, and particularly preferably in the range of 25 μmol / g to 35 μmol / g. Within the above range, sufficient moldability and mechanical properties can be obtained.

[0018] Examples of aliphatic homopolyamide resins having an average carbon atom number of more than 6 per amide group include polyenantholactam (polyamide 7), polyundecane lactam (polyamide 11), polylauryllactam (polyamide 12), polytetramethylene dodecamide (polyamide 412), polypentamethylene adipamide (polyamide 56), polypentamethylene azelamide (polyamide 59), polypentamethylene sebacamide (polyamide 510), polypentamethylene sebacamide (polyamide 511), polypentamethylene sebacamide (polyamide 512), polypentamethylene sebacamide (polyamide 513), polypentamethylene sebacamide (polyamide 514), polypentamethylene sebacamide (polyamide 515), polypentamethylene sebacamide (polyamide 516), polypentamethylene sebacamide (polyamide 517), polypentamethylene sebacamide (polyamide 518), polypentamethylene sebacamide (polyamide 519), polypentamethylene sebacamide (polyamide 520), polypentamethylene sebacamide (polyamide 521), polypentamethylene sebacamide (polyamide 522), polypentamethylene sebacamide (polyamide 523), polypentamethylene sebacamide (polyamide 524), polypentamethylene sebacamide (polyamide 525), polypentamethylene sebacamide (polyamide 526), ​​polypentamethylene sebacamide (polyamide 527), polypentamethylene sebacamide (polyamide 528), polypentamethylene sebacamide (polyamide 529 ... Polyhexamethylene dodecamide (Polyamide 512), Polyhexamethylene suberamide (Polyamide 68), Polyhexamethylene azelamide (Polyamide 69), Polyhexamethylene sebacamide (Polyamide 610), Polyhexamethylene undecamide (Polyamide 611), Polyhexamethylene dodecamide (Polyamide 612), Polyhexamethylene tetradecamide (Polyamide 614), Polyhexamethylene hexadecaamide (Polyamide 616), Polyhexamethylene Polynonamethylene octadecamide (polyamide 618), polynonameethylene adipamide (polyamide 96), polynonameethylene suberamide (polyamide 98), polynonameethylene azelamide (polyamide 99), polynonameethylene sebacamide (polyamide 910), polynonameethylene dodecamide (polyamide 912), polydecamethylene adipamide (polyamide 106), polydecamethylene suberamide (polyamide 108), polydecamethylene azelamide ( Polyamide 109), polydecamethylene sebacamide (polyamide 1010), polydecamethylene dodecamide (polyamide 1012), polydodecamethylene adipamide (polyamide 126), polydodecamethylene suberamide (polyamide 128), polydodecamethylene azelamide (polyamide 129), polydodecamethylene sebacamide (polyamide 1210), polydodecamethylene dodecamide (polyamide 1212), polyamide 122, etc.

[0019] Aliphatic copolyamide resins having an average carbon atom number of more than 6 per amide group include copolymers using several kinds of raw material monomers that form aliphatic homopolyamide resins having an average carbon atom number of more than 6 per amide group, as well as caprolactam / hexamethylenediaminoazelaic acid copolymer (polyamide 6 / 69), caprolactam / hexamethylenediaminosebacic acid copolymer (polyamide 6 / 610), caprolactam / hexamethylenediaminoundecanedicarboxylic acid copolymer (polyamide 6 / 611), caprolactam / hexamethylenediaminododecanedicarboxylic acid copolymer ( Examples of the copolymer include polyamide 6 / 612), caprolactam / aminoundecanoic acid copolymer (polyamide 6 / 11), caprolactam / lauryllactam copolymer (polyamide 6 / 12), caprolactam / hexamethylenediaminoadipic acid / lauryllactam copolymer (polyamide 6 / 66 / 12), caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminosebacic acid copolymer (polyamide 6 / 66 / 610), and caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 / 66 / 612).

[0020] Among these, from the viewpoint of suppressing water absorption, the aliphatic polyamide resin (A) is preferably at least one selected from the group consisting of at least one homopolymer selected from the group consisting of polynonamethylene dodecamide (polyamide 912), polydecamethylene sebacamide (polyamide 1010), polydecamethylene dodecamide (polyamide 1012), polydodecamethylene dodecamide (polyamide 1212), polyundecaneamide (polyamide 11), and polydodecanamide (polyamide 12), and at least one copolymer selected from the group consisting of polyamide 6 / 12 copolymer and polyamide 6 / 6 / 12 copolymer, and more preferably polydodecanamide (polyamide 12).

[0021] The aliphatic polyamide resin (A) is contained in an amount of 55 to 78% by mass, preferably 58 to 70% by mass, based on 100% by mass of the polyamide resin composition. If the content of the aliphatic polyamide resin (A) is less than the above range, molding processing becomes difficult, whereas if it is more than the above range, the mechanical properties are not sufficiently exhibited.

[0022] <Glass Fiber (B)> The polyamide resin composition contains glass fiber (B). The fiber refers to a shape having a fiber length of 0.3 mm or more and an aspect ratio (ratio of fiber length / diameter) of 10 or more. As described below, the glass fiber (B) in the polyamide resin composition includes glass fiber (B) that has been broken by melt-kneading. Therefore, the content of glass fiber (B) in the polyamide resin composition also includes glass fiber (B) that has been broken and therefore no longer meets the definition of "fiber" in this specification. The content of glass fiber (B) in the polyamide resin composition corresponds to the amount of glass fiber blended as a raw material. The glass fiber (B) may be surface-treated with a surface treatment agent and / or a binder. Furthermore, to improve workability, the glass fiber (B) may be converged or granulated with these surface treatment agents. Examples of surface treatment agents and binders include various coupling agents such as silane coupling agents, titanium-based coupling agents, aluminum-based coupling agents, and zirconia-based coupling agents; water glass, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, starch, polyvinyl alcohol, acrylic resins, epoxy resins, phenolic resins, polyvinyl acetate, polyurethane resins, epoxy compounds, isocyanate compounds, colloidal silica, colloidal alumina, fatty acids, surfactants, etc. The surface treatment agents and binders may be used alone or in combination of two or more.

[0023] The surface treatment agent and binder may be applied to the glass fiber (B) in advance, dried, and subjected to a surface treatment or a binder treatment, or may be added simultaneously with the glass fiber (B) during preparation of the resin composition.

[0024] The glass fibers used as the raw material may have an average fiber diameter of 3 to 23 μm. From the viewpoint of the dimensional stability and mechanical properties of a molded article made from the composition, the average fiber diameter is preferably 6 to 23 μm, and for example, an average fiber diameter of 10 to 23 μm can be used.

[0025] The glass fibers may be used alone or in combination of two or more. Two or more types of glass fibers having different average fiber diameters may be used. An example of a combination of glass fiber diameters is a combination of (B1) glass fibers having an average fiber diameter of 6 to 11 μm and (B2) glass fibers having an average fiber diameter of 13 to 25 μm.

[0026] The length (cut length) of the glass fibers as the raw material is not particularly limited, and chopped strands cut to 1 mm to 50 mm can be used, with 3 mm to 10 mm being more preferable from the viewpoint of productivity. The average fiber length of the glass fibers in the polyamide resin composition is not particularly limited, and is preferably 50 μm to 1,000 μm, and from the viewpoint of mechanical properties and of sufficiently defibrating the glass fibers and dispersing them uniformly in the material, is more preferably 100 μm to 500 μm, and even more preferably more than 200 μm and 400 μm or less.

[0027] The above-mentioned values ​​of the average fiber diameter of the glass fibers and the glass fiber length (cut length) of the raw material are values ​​before melt-kneading with polyamide. The value of the average fiber length of the glass fibers in the polyamide resin composition is a value after melt-kneading with polyamide. The value after melt-kneading takes into account the case where at least a part of the glass fibers are broken and dispersed in the composition during melt-kneading of the raw materials in the production process of the polyamide composition.

[0028] The average fiber diameter and cut length of the raw glass fibers can be observed using an optical microscope. The average fiber diameter and cut length of the raw glass fibers (B) may be catalog values.

[0029] The average fiber length of the glass fibers in the polyamide resin composition can be measured by dissolving the polyamide resin in a solvent, separating the polyamide resin from the polyamide resin composition, and then observing the result with an optical microscope. The lengths of approximately 1,000 arbitrarily selected glass fibers are measured from the observed image using image analysis software, and the average value is calculated to be the average fiber length.

[0030] Examples of commercially available glass fibers include products manufactured by Nippon Electric Glass Co., Ltd. under the product names ECS 03T-249, ECS 03T-249H, ECS 03T-275, ECS 03T-275H, ECS 03T-289, ECS 03T-289H, ECS 03T-289DE, ECS 03T-920EW, and HP3610XM, and products manufactured by Nitto Boseki Co., Ltd. under the product names CS 3DE-456S, CSG 3J-820, CSG 3PA-820S, CS 3SH-223, and CS 3PE-454.

[0031] The polyamide resin composition contains 20 to 35% by mass, preferably 25 to 33% by mass, of glass fiber (B) in 100% by mass. If the amount of glass fiber (B) is less than the above range, the mechanical properties will be poor. If the amount of glass fiber (B) is greater than the above range, molding processability may become difficult.

[0032] <Crosslinking Agent (C)> The polyamide resin composition contains a crosslinking agent (C). Examples of the crosslinking agent (C) include polyfunctional acrylic monomers, polyfunctional allylic monomers, and mixed monomers thereof. Further specific examples include, for example, common polyfunctional acrylic monomers such as ethylene oxide-modified bisphenol A di(meth)acrylate, 1,4-butanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, caprolactone-modified dipentaerythritol hexaacrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane triacrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, tris(methacryloxyethyl)isocyanurate, and mixtures thereof. In particular, tris(acryloxyethyl)isocyanurate (triacrylic acid ester of tris(2-hydroxyethyl)isocyanuric acid) is preferably used because of its low skin irritation.

[0033] Examples of polyfunctional allyl monomers include triallyl cyanurate, triallyl isocyanurate, trimethallyl isocyanurate, diallyl phthalate, diallyl benzene phosphonate, and mixtures thereof.

[0034] Among these, from the viewpoint of ease of crosslinking by electron beam irradiation, at least one selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, trimethallyl isocyanurate, diallyl phthalate, and diallyl benzene phosphonate is preferred.

[0035] If necessary, an initiator, a catalyst, a stabilizer, etc. may be added to the crosslinking agent. These initiators, catalysts, stabilizers, etc. may be added to the crosslinking agent or to the polyamide resin.

[0036] The crosslinking agent (C) is contained in an amount of 1 to 9% by mass, preferably 2 to 7% by mass, and more preferably 3 to 6% by mass, based on 100% by mass of the polyamide resin composition. If the amount of crosslinking agent (C) is less than the above range, the crosslinking state is insufficient, resulting in poor strength, such as tensile strength and tensile modulus. If the amount of crosslinking agent (C) is greater than the above range, it will have a negative effect on impact resistance, such as elongation and impact strength.

[0037] <Heat-resistant agent (D)> The polyamide resin composition contains a heat-resistant agent. As the heat-resistant agent, one that can improve the heat resistance and antioxidant resistance of the molded body can be used. Organic or inorganic heat-resistant agents can be used depending on the purpose, but inorganic heat-resistant agents are preferred. These may be used alone or in combination of two or more.

[0038] (1) Organic Heat Resistant Agent Examples of the organic heat resistant include phenolic compounds, phosphorus compounds, sulfur compounds, nitrogen compounds, etc. These may be used alone or in combination of two or more.

[0039] (Phenol Compound) Preferred examples of the phenol compound include hindered phenol compounds. In this specification, a hindered phenol refers to a compound having a substituent at the ortho-position (hereinafter also referred to as the "o-position") of the phenolic hydroxyl group. The substituent at the o-position is not particularly limited, but examples include an alkyl group, an alkoxy group, an amino group, and a halogen atom. Among these, alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, an i-butyl group, and a t-butyl group are preferred, with bulky i-propyl group, sec-butyl group, an i-butyl group, and a t-butyl group being more preferred, and a t-butyl group being most preferred. Furthermore, with regard to the o-position, it is preferred that both of the two o-positions relative to the phenolic hydroxyl group have a substituent.

[0040] Specific examples of hindered phenols having a t-butyl group at the o-position include N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), pentaerythritol-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate, ethylenebis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], and 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane. These may be used alone or in combination of two or more. Commercially available heat-resistant additives include "Irganox (registered trademark) 1010" (BASF) and "Sumilizer (registered trademark) GA-80" (Sumitomo Chemical Co., Ltd.). These may be used alone or in combination of two or more.

[0041] (Phosphorus Compound) The phosphorus compound is preferably a phosphite compound of a hindered phenol or a hypophosphite compound of a hindered phenol, more preferably a phosphite compound of a hindered phenol having a t-butyl group at the o-position or a hypophosphite compound of a hindered phenol having a t-butyl group at the o-position, and even more preferably a phosphite compound of a hindered phenol having a t-butyl group at the o-position. Specific examples of the phosphite compound of a hindered phenol having a t-butyl group at the o-position include tris(2,4-di-t-butylphenyl)phosphite and bis(2,6-di-t-butyl-4-methylphenyl)pentaerthritol diphosphite. Specific examples of hypophosphite ester compounds of hindered phenols having a t-butyl group at the o-position include reaction products of biphenyl, phosphorus trichloride, and 2,4-di-tert-butylphenol, with p,p,p',p'-tetrakis(2,4-di-tert-butylphenoxy)-4,4-biphenyldiphosphine as the main component. Commercially available heat-resistant additives include "Irgafos (registered trademark) 168" (BASF) and "Hostanox (registered trademark) P-EPQ" (Clariant Chemicals). These may be used alone or in combination of two or more.

[0042] (Sulfur-Based Compounds) Examples of sulfur-based compounds include distearyl-3,3-thiodipropionate, pentaerythrityl tetrakis(3-laurylthiopropionate), and didodecyl(3,3′-thiodipropionate). These may be used alone or in combination of two or more.

[0043] (Nitrogen-based Compound) Examples of the nitrogen-based compound include melamine, melamine cyanurate, benguanamine, dimethylol urea, and cyanuric acid. These may be used alone or in combination of two or more.

[0044] As the organic heat-resistant agent, from the viewpoint of coloring of the material, phenol-based compounds and phosphorus-based compounds are preferred, and hindered phenol-based compounds are more preferred.

[0045] (2) Inorganic Heat Resistant Inorganic heat resisting agents include copper compounds and potassium halides. Examples of copper compounds include cuprous iodide, cuprous bromide, cupric bromide, and copper acetate. Cuprous iodide is preferred from the viewpoint of heat resistance and metal corrosion inhibition. Examples of potassium halides include potassium iodide, potassium bromide, and potassium chloride. Potassium iodide and / or potassium bromide are preferred from the viewpoint of heat resistance and long-term stability of the inorganic heat resisting agent. These may be used alone or in combination of two or more. For example, a combination of cuprous iodide with potassium iodide and / or potassium bromide is preferred. Furthermore, the use of a nitrogen-containing compound such as melamine, melamine cyanurate, benguanamine, dimethylol urea, or cyanuric acid in combination is more effective.

[0046] The heat-resistant agent (D) is contained in an amount of 0.1 to 1.5% by mass, more preferably 0.2 to 1.3% by mass, and even more preferably 0.3 to 1.2% by mass, based on 100% by mass of the polyamide resin composition. If the amount of the heat-resistant agent is less than the above range, thermal deterioration of the molded article may occur, whereas if the amount is more than the above range, the heat-resistant agent may bleed out from the molded article.

[0047] <Inorganic Filler (E) Other Than Glass Fiber> The polyamide resin composition preferably contains an inorganic filler other than glass fiber as an optional component. Examples of inorganic fillers include wollastonite, potassium titanate whiskers, zinc oxide whiskers, carbon fibers, alumina fibers, silicon carbide fibers, ceramic fibers, asbestos fibers, gypsum fibers, and metal fibers; silicates such as sericite, kaolin, mica, clay, bentonite, asbestos, talc, and alumina silicate; swellable layered silicates such as montmorillonite and synthetic mica; metal compounds such as alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, and iron oxide; carbonates such as calcium carbonate, magnesium carbonate, and dolomite; sulfates such as calcium sulfate and barium sulfate; glass flakes, glass beads, ceramic beads, boron nitride, silicon carbide, calcium phosphate, and silica. Preferably, the inorganic filler is at least one selected from the group consisting of silica, talc, and milled glass fiber. These fillers may be used alone or in combination.

[0048] The average particle size of talc is preferably 1 to 20 μm, more preferably 2 to 15 μm. The average particle size of talc is the average particle size measured by a particle size distribution measurement method using a laser diffraction / scattering method. An example of a measuring device is the laser diffraction particle size distribution measuring device SALD-7000 manufactured by Shimadzu Corporation. When a commercially available product is used as the talc, the catalog value of the commercially available product is used as the average particle size of the talc.

[0049] The average fiber length of the glass milled fiber is measured after grinding each fiber, and is preferably 10 to 200 μm, more preferably 30 to 150 μm. The average fiber length can be determined, for example, using a glass fiber length measuring device, but when a commercially available product is used as the glass milled fiber, the catalog value of the commercially available product is used. The fiber diameter of the glass milled fiber is preferably 2 to 30 μm, more preferably 5 to 15 μm. The fiber diameter of the glass milled fiber can be determined, for example, using an image analyzer by observing with an optical microscope, but when a commercially available product is used as the glass milled fiber, the catalog value of the commercially available product is used.

[0050] The inorganic filler (E) other than glass fiber is contained in an amount of 0 to 6 mass%, preferably 0.5 to 5 mass%, more preferably 1 to 4 mass%, based on 100 mass% of the polyamide resin composition. When the content of the inorganic filler (E) other than glass fiber is within the above range, the mechanical properties of the molded product are improved.

[0051] Depending on the purpose, the polyamide resin composition may contain, as optional components, functionality-imparting agents such as dyes, pigments, particulate reinforcements, plasticizers, antioxidants, foaming agents, weather resistance agents, crystal nucleating agents, crystallization accelerators, lubricants, antistatic agents, flame retardants, flame retardant assistants, and colorants. Among these, those that also function as inorganic fillers are included in the inorganic fillers of the present invention. Those that function as heat resistance agents are included in the heat resistance agents. The optional additives may be included in an amount of preferably 0.01 to 1 mass %, more preferably 0.05 to 0.5 mass %, based on 100 mass % of the polyamide resin composition.

[0052] The polyamide resin composition may contain a thermoplastic resin other than the aliphatic polyamide resin (A). From the viewpoints of mechanical properties and moldability, the content of the thermoplastic resin other than the aliphatic polyamide resin (A) is preferably 2% by mass or less, more preferably less than 0.1% by mass, and even more preferably zero, relative to 100% by mass of the polyamide resin composition.

[0053] <Method for Producing Polyamide Resin Composition> The method for producing the polyamide resin composition is not particularly limited, and the following method can be applied, for example. A commonly known melt-kneading machine such as a single-screw or twin-screw extruder, a Banbury mixer, a kneader, or a mixing roll is used to mix the aliphatic polyamide resin (A), the glass fiber (B), the crosslinking agent (C), the heat-resistant agent (D), and other optional components. For example, any of the following methods may be used: a method using a twin-screw extruder to blend all of the raw materials and then melt-knead them; a method using a twin-screw extruder to blend some of the raw materials and then melt-knead them, and then blending and melt-kneading the remaining raw materials; or a method using a side feeder to blend some of the raw materials and then mixing the remaining raw materials during melt-kneading.

[0054] [Molded articles of polyamide resin composition and uses thereof] The polyamide resin composition can be suitably used for producing injection-molded articles by injection molding, extrusion-molded articles by extrusion molding, blow-molded articles by blow molding, and rotation-molded articles by rotational molding. The polyamide resin composition has good injection moldability, so it can be suitably used for producing injection-molded articles by injection molding.

[0055] The method for producing an injection-molded article from the polyamide resin composition by injection molding is not particularly limited, and any known method can be used, for example, a method conforming to ISO 294-1.

[0056] The method for producing an extrusion molded article from the polyamide resin composition by extrusion molding is not particularly limited, and known methods can be used. It is also possible to obtain a multilayer structure by co-extrusion with a polyolefin such as polyethylene or another thermoplastic resin, followed by blow molding. In this case, an adhesive layer can be provided between the polyamide resin composition layer and the other thermoplastic resin layer such as polyolefin. In the case of a multilayer structure, the polyamide resin composition of the present invention can be used in either the outer layer or the inner layer.

[0057] The method for producing a blow-molded article from a polyamide resin composition by blow molding is not particularly limited, and known methods can be used. Generally, a parison is formed using a conventional blow molding machine, and then blow molding is carried out. The resin temperature during parison formation is preferably in the range of 10°C to 70°C higher than the melting point of the polyamide resin composition.

[0058] The method for producing a rotational molded article from the polyamide resin composition by rotational molding is not particularly limited, and any known method can be used. For example, the method described in WO 2019 / 054109 can be taken into consideration.

[0059] Examples of suitable applications of the injection-molded articles produced by injection molding, extrusion-molded articles produced by extrusion molding, blow-molded articles produced by blow molding, and rotational molded articles produced by rotational molding include, but are not limited to, automotive parts such as spoilers, air intake ducts, intake manifolds, resonators, fuel tanks, gas tanks, hydraulic oil tanks, fuel filler tubes, fuel delivery pipes, and various other hoses, tubes, and tanks; mechanical parts such as power tool housings and pipes; electrical and electronic parts such as tanks, tubes, hoses, and films; household and office supplies; building materials; and furniture parts. Furthermore, the resins are suitable for use in parts used in environments where the temperature fluctuates greatly, such as parts with heat resistance, cold resistance, and the like, for example, drive parts such as gears and belts in the automotive field, and sliding parts such as tire sidewalls and belts. Among these, the resins are suitable for use in automotive parts, sliding parts, and electrical and electronic parts.

[0060] Furthermore, since the polyamide resin composition has excellent gas barrier properties, it is suitable for use in molded articles that come into contact with high-pressure gas, such as tanks, tubes, hoses, films, etc. The type of gas is not particularly limited and examples thereof include hydrogen, nitrogen, oxygen, helium, methane, butane, and propane, with gases having low polarity being preferred, and hydrogen, nitrogen, and methane being particularly preferred.

[0061] It is also possible to obtain a multilayer structure by co-extrusion with a polyolefin such as polyethylene or another thermoplastic resin, followed by blow molding. In this case, an adhesive layer can be provided between the polyamide resin composition layer and the other thermoplastic resin layer such as polyolefin. In the case of a multilayer structure, the polyamide resin composition of the present invention can be used in either the outer layer or the inner layer.

[0062] The density of a molded article made of the polyamide resin composition is preferably 1.20 to 1.28 g / ml, more preferably 1.22 to 1.26 g / ml. When the density is in this range, the molded article has good mechanical properties.

[0063] <Cross-linked polyamide resin composition> The polyamide resin composition is also preferably used as a cross-linked polyamide resin composition by irradiating a molded article made of the polyamide resin composition with active energy rays. Examples of active energy rays include ultraviolet rays, electron beams, α-rays, β-rays, ion beams, particle beams, X-rays, and γ-rays, with ultraviolet rays and electron beams being preferred.

[0064] Examples of light sources that can be used for ultraviolet rays include xenon lamps, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, carbon arc lamps, and tungsten lamps. The irradiation time can be varied as appropriate depending on conditions such as the type of compound having a polymerizable unsaturated bond, the type of photopolymerization initiator, the coating thickness, and the ultraviolet light source. From the viewpoint of workability, irradiation for 1 to 60 seconds is preferred. Furthermore, heat treatment can be carried out after ultraviolet irradiation in order to complete the curing reaction. The irradiation dose of ultraviolet rays used to cure the composition of the present invention is 300 to 3,000 mJ / cm from the viewpoints of fast curing and workability. 2 is preferred.

[0065] Electron beams or the like can also be used as the active energy rays. When curing is performed using electron beams, a photopolymerization initiator does not need to be added, and it is preferable to use an electron beam accelerator having an energy of 100 to 500 eV.

[0066] The density of a crosslinked polyamide resin composition molded article after electron beam irradiation is preferably 1.20 to 1.28 g / ml, more preferably 1.22 to 1.26 g / ml. When the density is in the above range, the crosslinked article has good mechanical properties.

[0067] The uses of the crosslinked polyamide resin composition include the same uses as those of the molded articles of the polyamide resin composition described above.

[0068] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The values ​​of the examples, comparative examples, and raw materials were measured by the following methods.

[0069] <Relative Viscosity> This is a value measured at 25°C in accordance with JIS K6920-2 by dissolving 1 g of polyamide resin in 100 ml of 96% concentrated sulfuric acid.

[0070] <Terminal Amino Group Concentration> A polyamide resin was dissolved in a mixed solvent of phenol and methanol, and the terminal amino group concentration was determined by neutralization titration.

[0071] <Melting Point> In accordance with ISO 11357-3, a differential scanning calorimeter was used to heat a sample to a temperature equal to or higher than the expected melting point, and then the sample was cooled to 30°C at a rate of 10°C per minute, allowed to stand for about 1 minute, and then heated at a rate of 20°C per minute. The peak temperature of the melting curve measured was taken as the melting point. A value of less than 200°C before electron beam irradiation was considered to be acceptable, and a value of less than 200°C after electron beam irradiation was considered to be unacceptable.

[0072] <Density> Measured in accordance with ISO 1183-3 (gas pycnometer method) using an ISO TYPE-B test piece obtained by injection molding a polyamide resin composition, and the value before electron beam irradiation was 1.28 g / cm ３ The value after electron beam irradiation was 1.28 g / cm ３ Anything less than this was considered a pass.

[0073] <Water absorption rate> An ISO TYPE-A test piece obtained by injection molding a polyamide resin composition was immersed in water at 80°C for 24 hours, and the water absorption rate was calculated from the difference in mass of the test piece before and after immersion. A value of less than 1.0% before electron beam irradiation was considered acceptable, and a value of less than 1.0% after electron beam irradiation was considered acceptable.

[0074] <Mechanical Properties> The polyamide resin composition and the polyamide resin composition obtained by irradiating with electron beam were injection molded to prepare ISO TYPE-A test pieces and ISO TYPE-B test pieces, respectively, and the following mechanical properties were measured using these test pieces.

[0075] (1) Tensile strength and tensile breaking strain: Measurements were made at 23°C using an Instron tensile testing machine, model 5567, in accordance with ISO 527. A tensile strength of over 120 MPa before electron beam irradiation was considered acceptable, and a tensile breaking strain of 125 MPa or more after electron beam irradiation was considered acceptable. A tensile breaking strain of 8% or less before electron beam irradiation was considered acceptable, and a tensile breaking strain of 6% or less after electron beam irradiation was considered acceptable.

[0076] (2) Flexural Strength and Flexural Modulus Measurements were made at 23°C using an Instron tensile tester, model 5567, according to a method in accordance with ISO 178. A flexural strength of over 180 MPa before electron beam irradiation was considered acceptable, and a flexural modulus of over 185 MPa after electron beam irradiation was considered acceptable. A flexural modulus of over 6,300 MPa before electron beam irradiation was considered acceptable, and a flexural modulus of over 6,500 MPa after electron beam irradiation was considered acceptable.

[0077] (3) Charpy impact strength: Measured at 23°C using an Instron tensile tester, model 5567, in accordance with ISO 527-2 / 1A / 50. The value before electron beam irradiation was 18 kJ / m ２ The value after electron beam irradiation was 17 kJ / m ２ The above is considered a pass.

[0078] (4) Rockwell hardness (M scale) Measured at 23°C in accordance with ISO 6508-1 using an electric digital Rockwell hardness tester model ARD-P manufactured by Akashi Seisakusho Co., Ltd. A value of 55 or more before electron beam irradiation was considered acceptable, and a value of 63 or more after electron beam irradiation was considered acceptable.

[0079] From the above measured values, a comprehensive evaluation was made according to the following criteria: ◯: Meets all of the pass criteria for each of the above measured values. ×: Does not meet one or more of the pass criteria for each of the above measured values.

[0080] [Examples 1 to 4, Comparative Examples 1 to 5] The components listed in Table 1 were melt-kneaded in a twin-screw kneader ZSK32-Mc with a cylinder diameter of 32 mm and L / D of 47 at a cylinder temperature of 220°C, a screw rotation of 220 rpm, and a discharge rate of 40 kg / hr to produce the desired polyamide resin composition pellets. Test pieces were prepared from the obtained polyamide resin composition pellets using the method described above and used for evaluation before electron beam irradiation. The test pieces used in the evaluation before electron beam irradiation were irradiated with an electron beam of 100 kGy and electron beam energy of 4.8 MeV and used for evaluation after electron beam irradiation. The results are shown in Table 1. Note that the units of composition in the table are % by mass, and the entire resin composition is taken as 100% by mass.

[0081] The components used in Table 1 are as follows: PA12 (1): Polyamide 12, relative viscosity 2.2, melting point 179 ° C, terminal amino group concentration 33 μmol / g, manufactured by Ube Industries, Ltd. PA12 (2): Polyamide 12, relative viscosity 2.2, melting point 179 ° C, terminal amino group concentration 22 μmol / g, manufactured by Ube Industries, Ltd. PA12 (3): Polyamide 12, relative viscosity 2.5, melting point 178 ° C, terminal amino group concentration 23 μmol / g, manufactured by Ube Industries, Ltd. PA12 (4): Polyamide 12, relative viscosity 1.9, melting point 179 ° C, terminal amino group concentration 27 μmol / g, manufactured by Ube Industries, Ltd. PA6: Polyamide 6, relative viscosity 2.6, melting point 220 ° C, terminal amino group concentration 36 μmol / g, manufactured by Ube Industries, Ltd. Glass fiber (1): CSG 3J-820, E-glass, cut length 3 mm, cross-sectional shape: flat Average fiber diameter 10 μm (catalog value), binder component: urethane and acid copolymer (manufactured by Nippon Electric Glass Co., Ltd.) Crosslinking agent and inorganic filler: WH-60 (registered trademark) (manufactured by Mitsubishi Chemical Corporation). This product contains 60% by weight of the crosslinking agent triallyl isocyanurate, and the remaining 40% by weight is inorganic filler. Heat-resistant agent: 1:6 mixture of cuprous iodide and potassium iodide. Crystallization accelerator (inorganic filler): MicroAce (registered trademark) L-1, average particle size D50: 5 μm (manufactured by Nippon Talc Co., Ltd.).

[0082]

[0083] Comparing Examples 1 to 5 with Comparative Example 1, it can be seen that when the amount of polyamide resin is less than the range of the present invention and the amount of glass fiber is greater, the density increases both before and after electron beam irradiation. Comparing Examples 1 to 5 with Comparative Example 2, it can be seen that when a crosslinking agent is not included and the amount of glass fiber is greater than the range of the present invention, the density increases both before and after electron beam irradiation. Comparing Examples 1 to 5 with Comparative Example 3, it can be seen that when a crosslinking agent is not included, the flexural strength and flexural modulus values ​​decrease both before and after electron beam irradiation. Comparing Examples 1 to 5 with Comparative Example 4, it can be seen that when polyamide 6 is used as the polyamide resin, the density increases both before and after electron beam irradiation and the water absorption rate increases. Comparing Examples 1 to 5 with Comparative Example 5, it can be seen that when glass fiber is not included, the flexural strength and flexural modulus values ​​decrease both before and after electron beam irradiation and the water absorption rate increases both before and after electron beam irradiation.

[0084] The polyamide resin composition can be used as an injection-molded article, an extrusion-molded article, a blow-molded article, or a rotation-molded article. These molded articles and crosslinked articles thereof are particularly suitable for use in automobile parts, sliding parts, or electric / electronic parts.

Claims

1. In 100% by mass of the polyamide resin composition, it contains 55 to 78% by mass of an aliphatic polyamide resin (A), 20 to 35% by mass of glass fiber (B), 1 to 9% by mass of a crosslinking agent (C), 0.1 to 1.5% by mass of a heat-resistant agent (D), and 0 to 6% by mass of an inorganic filler (E) other than glass fiber, wherein the aliphatic polyamide resin (A) is a polyamide resin composition in which the average number of carbon atoms per amide group is more than 6.

2. The polyamide resin composition according to claim 1, wherein the aliphatic polyamide resin (A) has a melting point measured in accordance with ISO 11357-3 of 170 to 210 °C.

3. The aliphatic polyamide resin (A) is at least one selected from the group consisting of at least one homopolymer selected from the group consisting of polynonamethylene dodecamide (polyamide 912), polydecamethylene sebacamide (polyamide 1010), polydecamethylene dodecamide (polyamide 1012), polydodecamethylene dodecamide (polyamide 1212), polyundecanamide (polyamide 11), and polydodecanamide (polyamide 12), and at least one copolymer selected from the group consisting of a polyamide 6 / 12 copolymer and a polyamide 6 / 66 / 12 copolymer. The polyamide resin composition according to claim 1.

4. The polyamide resin composition according to claim 1, wherein the crosslinking agent (C) is at least one selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, trimethaallyl isocyanurate, diallyl phthalate, and diallyl benzene phosphonate.

5. The polyamide resin composition according to claim 1, wherein the heat-resistant agent (D) is an inorganic heat-resistant agent.

6. The polyamide resin composition according to claim 1, wherein the terminal amino group concentration of the aliphatic polyamide resin (A) is 25 μmol / g or more and 60 μmol / g or less as the terminal amino group concentration determined by neutralization titration after dissolving in a mixed solvent of phenol and methanol.

7. The polyamide resin composition according to claim 1, which contains 3 to 9% by mass of the crosslinking agent (C) in 100% by mass of the polyamide resin composition.

8. The polyamide resin composition according to claim 1, wherein the glass fiber (B) is surface-treated with a surface treatment agent and / or a binder.

9. A molded article of the polyamide resin composition according to any one of claims 1 to 8.

10. A crosslinked polyamide resin composition obtained by irradiating a molded article of the polyamide resin composition according to claim 9 with active energy rays.

11. The crosslinked polyamide resin composition according to claim 10, having a density of 1.20 to 1.28 g / cm3.