JP2023029105A - Polyamide resin composition - Google Patents

Abstract

To provide a polyamide resin composition which is excellent in flowability and retention stability in molding.SOLUTION: A polyamide resin composition contains (A) a polyamide resin, (B) a carboxylic acid, (C) an ethylene-acrylate copolymer, and (C) a fatty acid amide, wherein a value obtained by dividing a spiral flow value in a flat pate spiral mold of a cavity width of 10 mm and a thickness of 2 mm under conditions of at a set temperature of 295°C, a mold temperature of 90°C and an injection pressure of 50 MPa by the formic acid relative viscosity RV of the polyamide resin composition having formic acid relative viscosity RV of 38 or more and less than 49 is 6.8 or more, a value obtained by dividing the spiral flow value by the formic acid relative viscosity RV of the polyamide resin composition having the formic acid relative viscosity RV of 30 or more and less than 38 is 10.0 or more, and a value obtained by dividing the spiral flow value by the formic acid relative viscosity RV of the polyamide resin composition having the formic acid relative viscosity RV of 20 or more and less than 30 is 11.0 or more.SELECTED DRAWING: None

Description

The present invention relates to polyamide resin compositions.

Polyamide resin has excellent mechanical properties (mechanical strength, rigidity, impact resistance, etc.), heat resistance, and chemical resistance. Used in various industrial fields. In recent years, in particular, good fluidity has been demanded along with thinning of automobile parts for the purpose of weight reduction for improving fuel efficiency and miniaturization and precision of electric and electronic parts.

In order to improve fluidity, viscosity is generally adjusted. Consideration is being made. Patent Document 1 proposes mixing a polyamide resin with a low-molecular-weight polyamide oligomer having less than 15 carbon atoms per amide group and a number-average molecular weight of 3,000 or less for the purpose of good fluidity. Patent Document 2 proposes mixing a polyamide resin with a low-molecular-weight polyamide oligomer having less than 10 carbon atoms per amide group for the purpose of good fluidity. Patent Document 3 proposes mixing a polyamide resin with a low-molecular-weight polyamide oligomer having less than 10 carbon atoms per amide group and a melting point of 280° C. for the purpose of good fluidity.

Low molecular weight polyamides can also be produced by adding molecular weight modifiers (eg, monocarboxylic acids, monoamines, etc.) during polymerization.

Further, Patent Document 4 proposes adding Struktol TR-063A (manufactured by Struktol of America) as a fluidity improver to improve the fluidity.

JP 2004-107576 A JP-A-5-194841 Japanese Patent Publication No. 2006-510780 WO2018/074495

However, in the methods described in Patent Documents 1 to 3, the addition of a low-molecular-weight polyamide oligomer reduces the thermal stability during molding, resulting in gas generation and mold deposits due to retention in the molding machine. There's a problem. In addition, in the method of adding a molecular weight modifier, for example, when a dicarboxylic acid or monocarboxylic acid is added, the terminal amino group content of the obtained polyamide is extremely low, so when glass fibers are blended However, there is a problem that the wettability between the polyamide and the glass fiber is deteriorated, and the desired mechanical strength cannot be obtained. Furthermore, in the method described in Patent Document 4, the thermal stability of the fluidity improver is low, so there are problems such as foaming during compounding, poor productivity, and low retention stability during injection molding.

The present invention has been made in view of the above circumstances, and provides a polyamide resin composition that is excellent in fluidity and retention stability during molding.

That is, the present invention includes the following aspects.
(1) A polyamide resin composition comprising (A) a polyamide resin, (B) a carboxylic acid, (C) an ethylene-acrylate copolymer, and (D) a fatty acid amide,
A flat spiral mold with a cavity width of 10 mm and a thickness of 2 mm for the polyamide resin composition having a formic acid relative viscosity RV of 38 or more and less than 49 under conditions of a set temperature of 295 ° C., a mold temperature of 90 ° C., and an injection pressure of 50 MPa. The value obtained by dividing the spiral flow value in the formic acid relative viscosity RV is 6.8 or more,
A flat spiral mold with a cavity width of 10 mm and a thickness of 2 mm for the polyamide resin composition having a formic acid relative viscosity RV of 30 or more and less than 38 under conditions of a set temperature of 295 ° C., a mold temperature of 90 ° C., and an injection pressure of 50 MPa. The value obtained by dividing the spiral flow value in the formic acid relative viscosity RV is 10.0 or more,
A flat spiral mold with a cavity width of 10 mm and a thickness of 2 mm for the polyamide resin composition having a formic acid relative viscosity RV of 20 or more and less than 30 under conditions of a set temperature of 295 ° C., a mold temperature of 90 ° C., and an injection pressure of 50 MPa. The value obtained by dividing the spiral flow value in the formic acid relative viscosity RV is 11.0 or more.
(2) The polyamide resin composition according to (1), further comprising (E) an inorganic filler.
(3) The polyamide resin composition according to (2), wherein the (E) inorganic filler is glass fiber.
(4) The polyamide resin composition according to (3), wherein the glass fiber content is 20% by mass or more and 60% by mass or less with respect to the total mass of the polyamide resin composition.
(5) The (A) polyamide resin is one or more selected from the group consisting of polyamide 66, polyamide 66/6I, polyamide 610, polyamide 612, polyamide 6I and polyamide 6, (1) to (4) The polyamide resin composition according to any one.
(6) The polyamide resin composition according to any one of (1) to (5), wherein the carboxylic acid (B) is adipic acid.
(7) The polyamide resin composition according to (6), wherein the adipic acid is granulated with a carrier polymer.
(8) The pH of the extracted water when the pellets of the polyamide resin composition are immersed in distilled water is 4.0 or more and 6.5 or less, according to any one of (1) to (7). Polyamide resin composition.
(9) The polyamide resin composition according to any one of (1) to (8), wherein (C) the ethylene-acrylate copolymer is an ethylene-methyl acrylate copolymer.
(10) The polyamide resin composition according to any one of (1) to (9), wherein the (D) fatty acid amide is ethylenebisstearylamide.

According to the polyamide resin composition of the above aspect, it is possible to provide a polyamide resin composition which is excellent in fluidity and retention stability during molding.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the gist thereof.

As used herein, polyamide means a polymer having an amide bond (--NHCO--) in its main chain.

<<Polyamide resin composition>>
The polyamide resin composition of this embodiment includes (A) a polyamide resin, (B) a carboxylic acid, (C) an ethylene-acrylate copolymer, and (D) a fatty acid amide. Hereinafter, these components may be abbreviated as components (A) to (D).

The value SFD/RV obtained by dividing the spiral flow value of the polyamide resin composition having a formic acid relative viscosity RV of 38 or more and less than 49 by the formic acid relative viscosity RV is 6.8 or more, preferably 7.0 or more, It is more preferably 7.2 or more, and even more preferably 7.4 or more. On the other hand, the upper limit of SFD/RV in a polyamide resin composition having a formic acid relative viscosity RV of 38 or more and less than 49 is not particularly limited, but may be 20.0 or 15.0, for example.
The value SFD / RV obtained by dividing the spiral flow value of the polyamide resin composition having a formic acid relative viscosity RV of 30 or more and less than 38 by the formic acid relative viscosity RV is 10.0 or more, preferably 11.0 or more, It is more preferably 11.5 or more, and even more preferably 12.0 or more. On the other hand, the upper limit of SFD/RV in a polyamide resin composition having a formic acid relative viscosity RV of 30 or more and less than 38 is not particularly limited, but may be, for example, 20.0 or 15.0.
The value SFD / RV obtained by dividing the spiral flow value of the polyamide resin composition having a formic acid relative viscosity RV of 20 or more and less than 30 by the formic acid relative viscosity RV is 11.0 or more, preferably 11.5 or more, It is more preferably 12.0 or more, and even more preferably 12.2 or more. On the other hand, the upper limit of SFD/RV in a polyamide resin composition having a formic acid relative viscosity RV of 20 or more and less than 30 is not particularly limited, but may be, for example, 30.0, and may be 20.0.

When SFD/RV in the numerical range of RV satisfies the respective ranges described above, fluidity and retention stability during molding are excellent.

The spiral flow value (SFD) is the flow length in a flat spiral mold with a cavity width of 10 mm and a thickness of 2 mm under conditions of a set temperature of 295° C., a mold temperature of 90° C. and an injection pressure of 50 MPa.

Also, the formic acid relative viscosity RV is obtained by adding the polyamide resin composition to formic acid and comparing the viscosity of the soluble component with the viscosity of the formic acid itself. Specifically, in accordance with ASTM-D789, using a solution of 8.4% by mass of polyamide resin dissolved in 90% by mass formic acid (10% by mass of water), formic acid relative at 25 ° C. Measure the viscosity RV.
Although the formic acid relative viscosity (RV) varies depending on the type of (A) polyamide resin to be blended, the RV of the polyamide resin composition is preferably more than 20 and less than 50, more preferably more than 24 and less than 42. When the RV of the polyamide resin composition is less than the above upper limit, it is possible to secure more fluidity and produce a thin molded article. On the other hand, when the RV of the polyamide resin composition is more than the above lower limit, the weighing time can be stabilized more during molding. In addition, the resin can be further suppressed from flowing out from the tip of the nozzle, the mechanical strength can be greatly improved, and the causes of gas generation and mold deposits due to deterioration of thermal stability can be further eliminated.

The polyamide resin composition of the present embodiment having the above configuration can provide a polyamide resin composition that is excellent in fluidity and retention stability during molding.

Next, each constituent component constituting the polyamide resin composition of the present embodiment will be described in detail.

<(A) Polyamide resin>
(A) Polyamide resins include, for example, polyamide 4 (polyα-pyrrolidone), polyamide 6 (polycaproamide), polyamide 11 (polyundecaneamide), polyamide 12 (polydodecanamide), polyamide 46 (polytetramethylene amide), Pamide), polyamide 56 (polypentamethylene adipamide), polyamide 66 (polyhexamethylene adipamide), polyamide 410 (polytetramethylene sebacamide), polyamide 412 (polytetramethylene dodecamide), polyamide 610 ( polyhexamethylene sebacamide), polyamide 612 (polyhexamethylene dodecamide), polyamide 1010 (polydecamethylene sebacamide), polyamide 1012 (polydecamethylene dodecamide), polyamide 6T (polyhexamethylene terephthalamide), polyamide 9T (polynonamethylene terephthalamide), polyamide 6I (polyhexamethylene isophthalamide), copolymers or mixtures thereof, and the like.

Among them, the (A) polyamide resin is preferably one or more selected from the group consisting of polyamide 66, polyamide 66/6I, polyamide 610, polyamide 612, polyamide 6I and polyamide 6, polyamide 66, polyamide 66 and A copolymer of polyamide 6I or a mixture of polyamide 66 and polyamide 6I is more preferred.
Polyamide 66 is a polyamide obtained by polycondensation of hexamethylenediamine and adipic acid, and is excellent in heat resistance, mechanical strength, and creep properties, and is suitably used for functional parts of automobiles, machines, and electrical products.

(A) Polyamide resins generally have an amino group or a carboxyl group at their terminal groups.
(A) The ratio of the amino terminal group amount to the total molar amount of the amino terminal group amount and the carboxy terminal group amount of the polyamide resin [amino terminal group amount/(amino terminal group amount + carboxy terminal group amount)] is 0.3 or more. It is preferably less than 1.0, more preferably 0.3 or more and 0.8 or less, and even more preferably 0.3 or more and 0.6 or less. When the terminal group amount ratio is within the above range, the molded article obtained from the polyamide resin composition tends to be more excellent in color tone, mechanical strength, and vibration fatigue resistance.

(A) The amino terminal group content of the polyamide resin is preferably 10 μmol/g or more and 100 μmol/g or less, more preferably 15 μmol/g or more and 80 μmol/g or less, and 30 μmol/g or more and 80 μmol/g or less. It is even more preferable to have When the amount of amino terminal groups is within the above range, the mechanical strength of the polyamide resin composition tends to be more excellent.

Here, methods for measuring the amount of amino terminal groups and the amount of carboxy terminal groups include ¹ H-NMR method and titration method. In the ¹ H-NMR method, it can be determined by integral values of characteristic signals corresponding to each terminal group. In the titration method, for amino terminal groups, a method of titrating a phenol solution of polyamide resin with 0.1N hydrochloric acid, for carboxy terminal groups, a method of titrating a benzyl alcohol solution of polyamide resin with 0.1N sodium hydroxide, etc. is mentioned.

A known method can be used as a method for adjusting the concentration of the terminal groups of the polyamide resin. The adjusting method is not particularly limited, but includes, for example, a method using a terminal adjusting agent. As a specific example, one or more terminal modifiers selected from the group consisting of monoamine compounds, diamine compounds, monocarboxylic acid compounds, and dicarboxylic acid compounds are added so as to achieve a predetermined terminal concentration during polymerization of the polyamide. is mentioned. The time at which the terminal modifier is added to the solvent is not particularly limited as long as the terminal modifier fulfills its original function.

Examples of the monoamine compound include, but are not limited to, aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine. alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine and naphthylamine; Among them, butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, or aniline are preferable from the viewpoint of reactivity, boiling point, stability of capped terminals, price, and the like. These may be used alone or in combination of two or more.

The diamine compound is not particularly limited, but examples include linear aliphatic diamines such as hexamethylenediamine and pentamethylenediamine; branched aliphatic diamines such as 2-methylpentanediamine and 2-ethylhexamethylenediamine. aromatic diamines such as p-phenylenediamine and m-phenylenediamine; and alicyclic diamines such as cyclohexanediamine, cyclopentanediamine and cyclooctanediamine. These may be used alone or in combination of two or more.

Examples of the monocarboxylic acid compound include, but are not limited to, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyl. Aliphatic monocarboxylic acids such as acids; Alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; Aromatics such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid Monocarboxylic acids and the like can be mentioned. These may be used alone or in combination of two or more.

Examples of the dicarboxylic acid compound include, but are not limited to, malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, and 2,2-dimethylglutaric acid. , 3,3-diethylsuccinic acid, azelaic acid, sebacic acid, suberic acid and other aliphatic dicarboxylic acids; 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids; isophthalic acid , 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, diphenic acid, diphenylmethane- Aromatic dicarboxylic acids such as 4,4′-dicarboxylic acid, diphenylsulfone-4,4′-dicarboxylic acid, and 4,4′-biphenyldicarboxylic acid are included. These may be used alone or in combination of two or more.

(A) The content of the polyamide resin can be, for example, 30.00% by mass or more and 90.00% by mass or less, and 40.00% by mass or more and 80.00% by mass, relative to the total mass of the polyamide resin composition. % by mass or less, and 45.00% by mass or more and 70.00% by mass or less.

<(B) Carboxylic acid>
By blending (B) carboxylic acid in the polyamide resin composition of the present embodiment, the molecular chain of (A) polyamide resin is cut to lower the viscosity and improve fluidity.

(B) Examples of carboxylic acids include adipic acid, pimelic acid, corcic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, oxaloacetic acid, and phthalic acid. , terephthalic acid, isophthalic acid, and 2-(10oxo-10H-9-oxa-10-phosphaphenanthren-10-ylmethyl)succinic acid. These may be used alone or in combination of two or more.
In addition to the above-mentioned dicarboxylic acid, monocarboxylic acid or tricarboxylic acid can also be expected to cut the molecular chain of the polyamide resin to lower the viscosity and increase the fluidity, but these carboxylic acids remain in the system. From the viewpoint of suppressing the occurrence of mold deposits during heating, it is preferable to use the above-described dicarboxylic acids.
Among them, (B) carboxylic acid is preferably adipic acid, sebacic acid or terephthalic acid, more preferably adipic acid.

(B) Carboxylic acid is preferably granulated in advance with a carrier polymer. In this case, the polymer used as the carrier is preferably a polymer in which the carboxylic acid is uniformly dispersed in the carrier, and it is preferred that the carrier and the carboxylic acid do not react. Such polymers include, for example, polymers composed of monomers such as ethylene, polypropylene, other olefins, methacrylic acid, vinyl acetate, acrylic acid, acrylic acid esters (acrylates), methacrylic acid esters (methacrylates), and copolymers thereof. etc. Among them, the carrier polymer is preferably an olefin-acrylate copolymer or an olefin-methacrylate copolymer, and more preferably (C) an ethylene-acrylate copolymer described later.

(B) The content of the carboxylic acid can be, for example, 0.10% by mass or more and 1.00% by mass or less, and 0.15% by mass or more and 0.80% by mass, relative to the total mass of the polyamide resin composition. It can be set to mass % or less, and can be set to 0.20 mass % or more and 0.60 mass % or less.

<(C) Ethylene-acrylate copolymer>
In the polyamide resin composition of the present embodiment, by blending (C) an ethylene-acrylate copolymer, (B) the carboxylic acid can be uniformly dispersed in the polyamide resin composition. In addition, since (C) ethylene-acrylate copolymer does not react with (B) carboxylic acid, as described above, it can also be used as a carrier polymer when granulating (B) carboxylic acid in advance.

Preferred (C) ethylene-acrylate copolymers include, for example, ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA), among others, ethylene-methyl acrylate copolymer. (EMA) is preferred.

(B) the carboxylic acid remains in the polyamide resin composition after extrusion in the presence of (C) the ethylene-acrylate copolymer. After dissolving the pellets of the polyamide resin composition with hexafluoroisopropanol (HFIP) and reprecipitating with acetonitrile, the supernatant was analyzed by liquid chromatography / mass spectrometry (LC / MS) measurement, It can be confirmed that (B) carboxylic acid is present in.

In addition, since the (B) carboxylic acid remains in the polyamide resin composition, when the pellets of the polyamide resin composition are immersed in distilled water, the pH of the extracted water becomes acidic. For example, when 30 mL of distilled water is added to 30 g of pellets and heated in an oven at 80° C. for 24 hours, the pH of the extracted water is measured and found to be on the acidic side. The acidity is proportional to the amount of carboxylic acid, and the pH of the extraction water is preferably 3.0 or more and 6.5 or less, more preferably 4.0 or more and 6.5 or less. When the pH of the extraction water is equal to or higher than the above lower limit, the acidity is not too high, and contamination of the inside of the molding machine and the mold during injection molding can be more effectively prevented. On the other hand, when the pH of the extraction water is equal to or less than the above upper limit, an appropriate amount of (B) carboxylic acid remains in the polyamide resin composition, and (A) the molecular chain of the polyamide resin is cut to lower the Viscosity can be increased and fluidity can be improved.

(C) The content of the ethylene-acrylate copolymer can be, for example, 0.10% by mass or more and 5.00% by mass or less, and 0.20% by mass or more and 3 00% by mass or less, and 0.40% by mass or more and 1.50% by mass or less.

Further, the content of (C) ethylene-acrylate copolymer is preferably higher than (B) carboxylic acid from the viewpoint of dispersing (B) carboxylic acid in the polyamide resin composition, and (C) The content ratio (B)/(C) of the carboxylic acid (B) to the ethylene-acrylate copolymer can be 1/4 or more and less than 1/1, and 1/3 or more and 2/3 or less, in terms of mass ratio. Preferably, 1/2 is more preferred.

<(D) fatty acid amide>
By blending the (D) fatty acid amide, the polyamide resin composition of the present embodiment can further improve the fluidity and appearance of the molded article.

(D) Fatty acid amides are amidated fatty acids. (D) Fatty acid amides include, for example, stearic acid amide, oleic acid amide, erucic acid amide, ethylenebisstearylamide, ethylenebisoleylamide, N-stearylstearylamide, N-stearylerucamide and the like. Among them, ethylenebisstearylamide or N-stearylerucamide is preferable, and ethylenebisstearylamide is more preferable.

(D) The content of the fatty acid amide can be, for example, 0.05% by mass or more and 1.50% by mass or less with respect to the total mass of the polyamide resin composition, and 0.05% by mass or more and 1.00% by mass. % by mass or less, and 0.08% by mass or more and 0.60% by mass or less.

<(E) Inorganic filler>
The polyamide resin composition of the present embodiment can obtain excellent mechanical strength and rigidity by further containing (E) an inorganic filler in addition to the above components (A) to (D).

(E) Inorganic fillers include, but are not limited to, glass fibers, carbon fibers, calcium silicate fibers, potassium titanate, aluminum borate, glass flakes, glass beads, talc, kaolin, Mica, hydrotalcite, calcium carbonate, zinc carbonate, zinc oxide, calcium monohydrogen phosphate, wollastonite, silica, zeolite, alumina, boehmite, aluminum hydroxide, titanium oxide, silicon oxide, magnesium oxide, calcium silicate, Sodium aluminosilicate, magnesium silicate, ketjen black, acetylene black, furnace black, carbon nanotubes, graphite, brass, copper, silver, aluminum, nickel, iron, calcium fluoride, mica, montmorillonite, swelling fluoromica, apatite, etc. is mentioned.
These may be used alone or in combination of two or more.

Among the above examples, from the viewpoint of increasing the mechanical strength and rigidity of the polyamide resin composition of the present embodiment, glass fiber, carbon fiber, glass flakes, glass beads, talc, kaolin, mica, calcium carbonate, monohydrogen phosphate At least one selected from the group consisting of calcium, wollastonite, silica, carbon nanotubes, graphite, calcium fluoride, montmorillonite, potassium titanate, swelling fluoromica, and apatite is preferred. Further, it is more preferably one or more selected from the group consisting of glass fibers, carbon fibers, glass flakes, glass beads, wollastonite, talc, mica, kaolin, calcium carbonate, and potassium titanate. is more preferred.

Among the above glass fibers and carbon fibers, from the viewpoint of imparting excellent mechanical properties to the polyamide resin composition, the number average fiber short diameter is 3 μm or more and 30 μm or less in the polyamide resin composition, and the weight average fiber length is It is preferably 100 µm or more and 750 µm or less, and the aspect ratio between the weight average fiber length and the number average fiber short diameter (value obtained by dividing the weight average fiber length by the number average fiber short diameter) is 10 or more and 100 or less.

Further, the glass fiber or carbon fiber may have a circular cross-section or a flattened shape (elliptical, cocoon-shaped, etc.). A flat shape is preferable from the viewpoint of low warpage.
When the fiber diameter of the glass fiber is flat, the number average fiber short diameter (also referred to as the average short diameter) is preferably 3 μm or more and 15 μm or less from the viewpoint of excellent mechanical strength, appearance, and low warpage. , 4 μm or more and 12 μm or less, and more preferably 5 μm or more and 11 μm or less.

Further, among the above wollastonites, from the viewpoint that excellent mechanical properties can be imparted to the polyamide resin composition, the polyamide resin composition has a number average fiber short diameter of 3 μm or more and 30 μm or less, and a weight average fiber length is 10 μm or more and 500 μm or less, and the aspect ratio between the weight average fiber length and the number average fiber short diameter (value obtained by dividing the weight average fiber length by the number average fiber short diameter) is preferably 3 or more and 100 or less. .

Further, among the talc, mica, kaolin, and silicon nitride, the number average particle diameter in the polyamide resin composition is 0.1 μm or more and 10 μm or less from the viewpoint that excellent mechanical properties can be imparted to the polyamide resin composition. Some are preferred.

Here, the number average fiber short diameter, number average particle diameter and weight average fiber length can be measured by the following methods.
Put the polyamide resin composition in an electric furnace, incinerate the contained organic matter, arbitrarily select 100 or more inorganic fillers from the residue, and examine with a SEM (Scanning Electron Microscope) or a microscope. The number average fiber short diameter is obtained by observing and measuring the fiber short diameter and particle diameter of these inorganic fillers, and dividing the total of the measured fiber short diameters and particle diameters by the number of inorganic fillers measured. And measure the number average particle size. In addition, the fiber length is measured using an SEM or microscope photograph at a magnification of 1000 times, and the weight average fiber length can be obtained by dividing the total measured fiber length by the weight of the measured inorganic filler. .
More specifically, weigh about 1 g of the polyamide resin composition, put it in a crucible in an electric furnace and burn it at 650 ° C. for 4 hours, cool it, put the remaining fiber on a glass plate, and use a microscope (manufactured by Keyence Corporation) Digital microscope VHX-5000, magnification: 1000 times) can be used to measure the number average fiber minor diameter, number average particle diameter and weight average fiber length of an arbitrarily selected inorganic filler.

The inorganic filler may be surface-treated with a silane coupling agent or the like.
Silane coupling agents include, but are not limited to, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane. mercaptosilanes such as γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane; epoxysilanes such as novolac epoxysilane; and vinylsilanes.
In particular, the silane coupling agent is preferably one or more selected from the group consisting of the above listed components, and more preferably aminosilanes from the viewpoint of improving mechanical strength due to wettability with polyamide.

Further, with respect to glass fibers and carbon fibers, as a sizing agent, a carboxylic acid anhydride-containing unsaturated vinyl monomer and an unsaturated vinyl monomer other than the carboxylic acid anhydride-containing unsaturated vinyl monomer are used as structural units. acid copolymers, epoxy compounds, polycarbodiimide compounds, polyurethane resins, homopolymers of acrylic acid, copolymers of acrylic acid and other copolymerizable monomers, and primary, secondary and tertiary amines thereof It may also contain salts with. These may be used alone or in combination of two or more.

Glass fibers and carbon fibers containing a sizing agent are obtained by continuously reacting them with a sizing agent in a known process for producing glass fibers and carbon fibers.
Specifically, by applying a sizing agent to glass fibers and carbon fibers using a known method such as a roller applicator and drying the produced fiber strands, glass fibers and carbon fibers containing a sizing agent are obtained. be done.
The fiber strands may be used as they are as rovings, or may be further subjected to a cutting process and used as chopped glass strands.

The sizing agent is preferably added (added) at a solid content rate of 0.2% by mass or more and 3% by mass or less with respect to 100% by mass of glass fiber or carbon fiber, and 0.3% by mass or more and 2% by mass or less. It is more preferable to give (add) equivalents.
When the addition amount of the sizing agent is equivalent to the above lower limit or more as a solid content with respect to 100% by mass of the glass fibers or the carbon fibers, the sizing of the glass fibers and the carbon fibers can be further maintained. On the other hand, when the amount of the sizing agent added is equal to or less than the above upper limit as a solid content with respect to 100% by mass of the glass fiber or carbon fiber, the thermal stability of the polyamide resin composition can be further improved.

Also, the drying of the strands may be performed after the cutting step, or the cutting step may be performed after drying the strands.

(E) The content of the inorganic filler is preferably 20% by mass or more, and 20% by mass or more and 70% by mass or less, relative to the total mass of the polyamide resin composition, from the viewpoint of mechanical strength and appearance. more preferably 20% by mass or more and 65% by mass or less, and particularly preferably 20% by mass or more and 60% by mass or less.

<(F) Lubricant>
In addition to the above components (A) to (D), the polyamide resin composition of the present embodiment further contains a lubricant other than the above (D) fatty acid amide (hereinafter sometimes simply referred to as "(F) lubricant"). can contain. By adding (F) a lubricant, fluidity and appearance can be further improved.

Examples of lubricants include, but are not particularly limited to, fatty acid metal salts, fatty acid esters, polyethylene wax, and the like. From the viewpoint of excellent appearance and moldability, one or more selected from the group consisting of fatty acid metal salts and fatty acid esters is preferred, and a combination of fatty acid metal salts and fatty acid esters is more preferred.

Fatty acids refer to aliphatic monocarboxylic acids. Among them, fatty acids having 8 or more carbon atoms are preferable, and fatty acids having 8 or more and 40 or less carbon atoms are more preferable.
Fatty acids include, but are not limited to, saturated or unsaturated, linear or branched, aliphatic monocarboxylic acids, more specifically stearic acid, palmitic acid, behenic acid, erucic acid, oleic acid, lauric acid, montanic acid and the like.

A fatty acid ester is an ester compound of the above fatty acid and alcohol.
Examples of alcohol include 1,3-butanediol, trimethylolpropane, stearyl alcohol, behenyl alcohol, lauryl alcohol and the like.
Examples of fatty acid esters include stearyl stearate, behenyl behenate, montanic acid-1,3-butanediol ester, montanic acid-trimethylolpropane ester, trimethylolpropane trilaurate, and butyl stearate. .

A fatty acid metal salt is a metal salt of the fatty acid described above.
Examples of metal elements that form salts with fatty acids include group 1 elements (alkali metals), group 2 elements (alkaline earth metals), group 3 elements, zinc, and aluminum in the periodic table.
Among them, as the metal element, alkali metals such as sodium and potassium, alkaline earth metals such as calcium and magnesium, and aluminum are preferable.
That is, fatty acid metal salts include, but are not limited to, calcium stearate, aluminum stearate, zinc stearate, magnesium stearate, calcium montanate, sodium montanate, aluminum montanate, and zinc montanate. , magnesium montanate, calcium behenate, sodium behenate, zinc behenate, calcium laurate, zinc laurate, calcium palmitate and the like.

Since the polyamide resin composition of the present embodiment also contains (D) fatty acid amide as a lubricant, the total content of (D) fatty acid amide and the above-described lubricant ((F) lubricant) other than fatty acid amide can be set. preferable. That is, the total content of (D) fatty acid amide and the above-described lubricant ((F) lubricant) other than fatty acid amide is, for example, 0.05% by mass or more and 1.50% by mass with respect to the total mass of the polyamide resin composition. % or less, 0.05 mass % or more and 1.00 mass % or less, or 0.08 mass % or more and 0.60 mass % or less.

<(G) Other additives>
The polyamide resin composition of the present embodiment may contain (G) other additives in addition to the above components (A) to (D). (G) Other additives include, for example, antioxidants, ultraviolet absorbers, heat stabilizers, photodegradation inhibitors, plasticizers, release agents, nucleating agents, flame retardants, colorants, other thermoplastic resins, etc. is mentioned.

Examples of the coloring agent include, but are not particularly limited to, carbon black, titanium oxide, and azine-based dyes. The content of these colorants is not particularly limited, but from the viewpoint of excellent appearance and moldability, it is preferably 0.01% by mass or more and 3.00% by mass or less with respect to the total mass of the polyamide resin composition. 0.05% by mass or more and 2.00% by mass or less is more preferable, and 0.10% by mass or more and 2.00% by mass or less is even more preferable.

<<Method for producing polyamide resin composition>>
The polyamide resin composition of the present embodiment can be produced by a method of kneading (A) the polyamide resin in a melted state using a single-screw or multi-screw extruder. (E) When inorganic fillers, especially chopped strand glass fibers, are used, a twin-screw extruder equipped with an upstream supply port and a downstream supply port is used, and a polyamide resin is supplied from the upstream supply port and melted. After that, a method of supplying chopped strand glass fibers from a downstream supply port and melt-kneading them can be preferably used. Further, when glass fiber rovings are used as the inorganic filler (E), they can be combined by a known method.

Further, (B) the carboxylic acid is pre-granulated with a carrier polymer, preferably (C) an ethylene-acrylate copolymer, and then (A) a polyamide resin, (D) a fatty acid amide, and, if necessary, ( E) A polyamide resin composition can also be produced by melt-kneading with an extruder together with an inorganic filler or the like. When all raw materials are melted and kneaded at once, a blending process of raw materials is required before feeding by feeders, or in the case of single feeding of raw materials, the number of feeders is insufficient, etc., resulting in productivity during mass production. may be restricted. Therefore, by granulating the carboxylic acid (B) with the ethylene-acrylate copolymer (C) in advance, productivity and flexibility during mass production are further improved.

<<Physical properties of the polyamide resin composition>>
(tensile strength)
The polyamide resin composition of the present embodiment has a tensile strength measured in accordance with ISO 527 of more than 195 MPa when the content of the inorganic filler is 30% by mass or more and less than 40% by mass. When the content is 40% by mass or more and 50% by mass or less, it is preferably over 240 MPa. The method for controlling the tensile strength above the lower limit is not particularly limited, but examples thereof include a method of using glass fiber as the inorganic filler, and a method of using an aminosilane compound as a coupling agent for the inorganic filler. be done.

≪Application≫
The polyamide resin composition of the present embodiment can be molded into molded articles for various parts by various conventionally known methods such as injection molding.

These various parts can be suitably used, for example, for automobiles, machinery industry, electricity and electronics, industrial materials, industrial materials, daily and household goods. In particular, the polyamide resin composition of the present embodiment has good fluidity, excellent mechanical strength, and excellent retention stability during molding, so that desired parts can be molded with high productivity.

EXAMPLES 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 those shown in these examples.

<raw materials>
((A) polyamide resin)
A-1: Polyamide 66 (formic acid relative viscosity RV: 48, TORZEN U4803 manufactured by INVIST)
A-2: Polyamide 66 (formic acid relative viscosity RV: 35) INVIST TORZEN U3500)
A-3: Polyamide 66/6I (formic acid relative viscosity RV: 28)
A-4: Polyamide 6I (formic acid relative viscosity RV: 14)

Polyamide A-3 was produced by carrying out a polyamide polymerization reaction by the “hot melt polymerization method” as follows.
1044 g of an equimolar salt of adipic acid and hexamethylenediamine, 456 g of an equimolar salt of isophthalic acid and hexamethylenediamine, and 0.5 mol % excess adipic acid relative to all equimolar salt components are dissolved in 1500 g of distilled water, An equimolar 50% by mass uniform aqueous solution of the raw material monomer was prepared.
While stirring at a temperature of 110° C. or higher and 150° C. or lower, the solution was concentrated by removing steam gradually until the solution concentration reached 70% by mass. After that, the internal temperature was raised to 220°C. At this time, the autoclave was pressurized to 1.8 MPa. The mixture was allowed to react for 1 hour while the pressure was maintained at 1.8 MPa by gradually removing water vapor until the internal temperature reached 245°C.
The pressure was then reduced over 1 hour. After that, the inside of the autoclave was maintained under a reduced pressure of 650 torr for 10 minutes. At this time, the final internal temperature of the polymerization was 265°C.
Then, it was pressurized with nitrogen to form a strand from a lower spinneret (nozzle), water-cooled, cut, discharged in pellet form, and dried at 100° C. for 12 hours in a nitrogen atmosphere to obtain polyamide A-3.

Polyamide A-4 was produced by carrying out the following polymerization reaction of polyamide by the “hot melt polymerization method”.
1,500 g of an equimolar salt of isophthalic acid and hexamethylenediamine, and 1.5 mol% excess adipic acid relative to all equimolar salt components are dissolved in 1,500 g of distilled water to prepare an equimolar 50% by mass uniform aqueous solution of the starting monomer. bottom.
While stirring at a temperature of 110° C. or higher and 150° C. or lower, the solution was concentrated by removing steam gradually until the solution concentration reached 70% by mass. After that, the internal temperature was raised to 220°C. At this time, the autoclave was pressurized to 1.8 MPa. The mixture was allowed to react for 1 hour while the pressure was maintained at 1.8 MPa by gradually removing water vapor until the internal temperature reached 245°C.
The pressure was then reduced over 30 minutes. After that, the inside of the autoclave was maintained under a reduced pressure of 650 torr for 10 minutes. At this time, the final internal temperature of the polymerization was 265°C.
Then, it was pressurized with nitrogen to form a strand from a lower spinneret (nozzle), cooled with water, cut, discharged in pellet form, and dried at 100° C. for 12 hours in a nitrogen atmosphere to obtain polyamide A-4.

((B) carboxylic acid)
B-1: adipic acid (ADA) (manufactured by Wako Pure Chemical Industries))

((C) ethylene-acrylate copolymer)
C-1: Ethylene-methyl acrylate copolymer (EMA) (manufactured by Japan Polyethylene Co., Ltd., trade name “Rescpearl EMA EB240H”)

((D) fatty acid amide)
D-1: Ethylene bisstearylamide (EBS) (manufactured by Lion Corporation, trade name “Armowax EBS powder”)

((E) inorganic filler)
E-1: Glass fiber (GF) (manufactured by Nippon Electric Glass Co., Ltd., trade name “ECS03T 275H/R”) (average fiber short diameter 10 μm, average fiber length 3 mm)

((G1) heat stabilizer)
G1-1: Hindered phenolic antioxidant (manufactured by BASF, trade name "IRGANOX1098")

((G2) flow improver)
G2-1: Struktol of America, trade name "Struktol TR-063A"

<Method for measuring physical properties>
[Physical properties 1]
(Formic acid relative viscosity RV)
Formic acid relative viscosity (RV) is compared with the viscosity of a solution (soluble matter) obtained by adding a polyamide resin or a polyamide resin composition obtained in Examples and Comparative Examples to formic acid (A) and the viscosity of formic acid itself. obtained by Specifically, it was carried out in accordance with ASTM-D789. More specifically, the formic acid relative viscosity (RV) was measured at 25° C. using a solution of 8.4% by mass of polyamide resin dissolved in 90% by mass formic acid (10% by mass of water).

[Physical properties 2]
(Spiral flow value (SFD))
Injection molding of the polyamide resin composition was performed under the following conditions, and the spiral flow value was measured. Before measuring the spiral flow, the pellets were dried at 100° C. for 16 hours or more and 24 hours or less, and the moisture content of the pellets was measured under the following conditions after confirming that it was less than 300 ppm by mass.

(Measurement condition)
Injection molding machine: "ALLROUNDER 370E" manufactured by ARBURG, mold clamping force 600kN
Mold for measurement: Spiral mold with internal groove width (cavity width) of 10 mm and thickness of 2 mm Mold temperature: 90°C
Set temperature: 295°C
Injection pressure: 50 MPa (injection speed is set to Max and controlled by pressure)
Injection time: 10 seconds Cooling time: 10 seconds

[Physical properties 3]
(SFD/RV)
For each polyamide resin composition, it was calculated by dividing the SFD obtained in physical property 2 by the RV obtained in physical property 1.

[Physical properties 4]
(pH of extracted water)
30 mL of distilled water is added to 30 g of pellets of each polyamide resin composition, and the pH of the extracted water after heating in an oven at 80 ° C. for 24 hours is measured with a pH meter (manufactured by HORIBA, product name "desktop type pH meter F-52"). and used as the pH value of the extraction water.

<Evaluation method>
[Evaluation 1]
(Tensile strength, tensile modulus, and tensile elongation)
First, for each polyamide resin composition, a 4 mm-thick dumbbell test piece specified by ISO294-1 was produced by an injection molding machine.

(Molding condition)
Injection molding machine: "ALLROUNDER 370E" manufactured by ARBURG, mold clamping force 600kN
Mold for measurement: Spiral mold with internal groove width (cavity width) of 10 mm and thickness of 2 mm Mold temperature: 90°C
Set temperature: 295°C
Injection speed: 100 mm/sec (controlled by injection speed)
Injection time: 15 seconds Cooling time: 10 seconds

Next, using the obtained 4 mm thick dumbbell test piece, a tensile test was performed at a tensile speed of 5 mm / min according to ISO 527, and tensile strength (MPa), tensile elastic modulus (GPa), and tensile elongation (%) were measured. It was measured.

[Evaluation 2]
(Charpy impact strength)
First, for each polyamide resin composition, a dumbbell test piece with a thickness of 4 mm was formed using the same method as in Evaluation 1. Then, using the obtained 4 mm thick dumbbell test piece, the Charpy impact strength with or without a notch was measured according to ISO179.

[Evaluation 3]
(retention stability)
Retention stability was evaluated using the following method. Specifically, first, when measuring the Charpy impact strength, after weighing with a molding machine, intentionally letting it stay for 9 minutes, using a 4 mm thick dumbbell test piece that was molded by injection, conforming to ISO 179 , Charpy impact strength without notch (value of Charpy impact strength without notch when intentionally retained for 9 minutes) was measured. In addition, as a control, a 4 mm thick dumbbell test piece that was molded by injection without intentional retention (0 minutes) after weighing was used to measure Charpy impact strength without notch (notch without intentional retention) in accordance with ISO179. Charpy impact strength) was measured. Then, the rate of decrease in the value of the unnotched Charpy impact strength when intentionally dwelled for 9 minutes relative to the unnotched Charpy impact strength when compared to the unnotched Charpy impact strength without intentional dwell (the above two notches The percentage of the value obtained by dividing the absolute value of the difference in Charpy impact strength without intentional retention by the Charpy impact strength without notch without intentional retention) was calculated, and the retention stability was evaluated for the reduction rate based on the following evaluation criteria.

(Evaluation criteria)
○: When the rate of decrease is less than 10% ×: When the rate of decrease is 10% or more

<Method for producing polyamide resin composition>
[Examples 1 to 8 and Comparative Examples 1 to 6]
(Production of Polyamide Resin Compositions PA-a1 to PA-a8 and PA-b1 to PA-b6)
Each polyamide resin composition was produced using the following method, except that the raw materials were blended so as to have the compositions shown in Tables 1 and 2.
As a method for producing a polyamide resin composition, the first barrel from the upstream side of the extruder has an upstream supply port, the fourth barrel has a downstream supply port, and the eleventh barrel has a vacuum devolatilization port. , L / D (extruder cylinder length / extruder cylinder diameter) = 48 (number of barrels: 12) twin-screw extruder (Coperion (Germany), ZSK-26MC), using the upstream side The temperature from the supply port to the die was set to 285° C., the screw rotation speed was 300 rpm to 450 rpm, the discharge rate was 50 kg/hour to 70 kg/hour, and the torque was always 80%. (A) Polyamide resin, (B) carboxylic acid, (C) ethylene-acrylate copolymer, (D) fatty acid amide or (G2) flow improver is supplied from the upstream supply port, and (E) inorganic from the downstream supply port. A filler (glass fiber) was supplied, and melt-kneaded under reduced pressure from a vacuum devolatilization port to prepare pellets of a polyamide resin composition.

The physical properties and evaluation results of each polyamide resin composition are shown in Tables 1 and 2 below. Tables 1 and 2 also show the unnotched Charpy impact strength values for the intentional residence times of 3 minutes, 6 minutes, and 9 minutes.

As shown in Table 1, polyamide resin compositions PA-a1 to PA-a8 (Examples 1 to 8 ) had good fluidity, mechanical strength, and retention stability during molding.
In addition, polyamide resin compositions PA-a1 and PA-a3 (Examples 1 and 3), and PA-a2 and PA-a4 (Example 2 and 4), the blending of (A) a polyamide resin with a lower formic acid relative viscosity RV tends to be superior in fluidity, tensile strength, tensile modulus, and notched Charpy impact strength, while , the tensile elongation tended to be more excellent when the (A) polyamide resin having a higher formic acid relative viscosity RV was blended.
In addition, polyamide resin compositions PA-a1 and PA-a2 (Examples 1 and 2), and PA-a3 and PA-a4 (implementation In the comparison of Examples 3 and 4), the lower the compounding ratio of components (B) to (D) to component (A), the more excellent the tensile strength, tensile modulus, and tensile elongation tended to be. There was a tendency that as the blending ratio of components (B) to (D) to component (A) increased, fluidity and notched Charpy impact strength tended to be more excellent.

On the other hand, as shown in Table 2, the polyamide resin compositions PA-b1 to PA-b6 (Comparative Examples 1 to 6) containing no component (B) or (C) had fluidity, mechanical strength, and moldability. A product with good retention stability over time was not obtained.

According to the polyamide resin composition of the present embodiment, it is possible to provide a polyamide resin composition that is excellent in fluidity and retention stability during molding. Therefore, the polyamide resin composition of the present embodiment can be suitably used for molding automobile parts and the like that are thin but require high reliability during long-term use.

Claims (10)

A polyamide resin composition comprising (A) a polyamide resin, (B) a carboxylic acid, (C) an ethylene-acrylate copolymer, and (D) a fatty acid amide,
A flat spiral mold with a cavity width of 10 mm and a thickness of 2 mm for the polyamide resin composition having a formic acid relative viscosity RV of 38 or more and less than 49 under conditions of a set temperature of 295 ° C., a mold temperature of 90 ° C., and an injection pressure of 50 MPa. The value obtained by dividing the spiral flow value in the formic acid relative viscosity RV is 6.8 or more,
A flat spiral mold with a cavity width of 10 mm and a thickness of 2 mm for the polyamide resin composition having a formic acid relative viscosity RV of 30 or more and less than 38 under conditions of a set temperature of 295 ° C., a mold temperature of 90 ° C., and an injection pressure of 50 MPa. The value obtained by dividing the spiral flow value in the formic acid relative viscosity RV is 10.0 or more,
A flat spiral mold with a cavity width of 10 mm and a thickness of 2 mm for the polyamide resin composition having a formic acid relative viscosity RV of 20 or more and less than 30 under conditions of a set temperature of 295 ° C., a mold temperature of 90 ° C., and an injection pressure of 50 MPa. The value obtained by dividing the spiral flow value in the formic acid relative viscosity RV is 11.0 or more. 2. The polyamide resin composition according to claim 1, further comprising (E) an inorganic filler. 3. The polyamide resin composition according to claim 2, wherein (E) the inorganic filler is glass fiber. 4. The polyamide resin composition according to claim 3, wherein the content of said glass fiber is 20% by mass or more and 60% by mass or less with respect to the total mass of said polyamide resin composition. The (A) polyamide resin is one or more selected from the group consisting of polyamide 66, polyamide 66/6I, polyamide 610, polyamide 612, polyamide 6I and polyamide 6, according to any one of claims 1 to 4 A polyamide resin composition as described. The polyamide resin composition according to any one of claims 1 to 5, wherein the (B) carboxylic acid is adipic acid. 7. The polyamide resin composition according to claim 6, wherein the adipic acid is granulated with a carrier polymer. The polyamide resin composition according to any one of claims 1 to 7, wherein the pH of the extracted water when the pellets of the polyamide resin composition are immersed in distilled water is 4.0 or more and 6.5 or less. The polyamide resin composition according to any one of claims 1 to 8, wherein the (C) ethylene-acrylate copolymer is an ethylene-methyl acrylate copolymer. The polyamide resin composition according to any one of claims 1 to 9, wherein the (D) fatty acid amide is ethylenebisstearylamide.