JP7249738B2 - Polyamide resin pellets, method for producing the same, and method for producing polyamide composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to polyamide resin pellets, a method for producing the same, and a method for producing a polyamide composition.

Polyamides represented by polyamide 6 (hereinafter sometimes abbreviated as "PA6") and polyamide 66 (hereinafter sometimes abbreviated as "PA66") are excellent in moldability, mechanical properties or chemical resistance. Because of its excellent properties, it is widely used as a material for various parts such as automobiles, electrical and electronic materials, industrial materials, daily and household items.
Polyamide 6I is an amorphous semi-aromatic polyamide into which an isophthalic acid component is introduced, and polyamide 66 is a crystalline aliphatic polyamide. It is known that it is possible to improve the resistance to toxic salt solutions (see, for example, Patent Document 1, etc.).
In order to produce a polyamide composition containing two or more types of such polyamides, the respective polyamide resin pellets and additives such as glass fibers are melt-kneaded by an extruder to produce pellets of the polyamide composition. is commonly used.

JP-A-63-205353

However, in the production of the polyamide composition containing the amorphous semi-aromatic polyamide and the crystalline aliphatic polyamide disclosed in Patent Document 1, the produced polyamide composition may be colored. In addition, strand breakage may occur during the production of pellets of the polyamide composition. Therefore, there were problems with the color tone and production stability of the polyamide composition.

The present invention has been made in view of the above circumstances, and a polyamide that can suppress coloration and strand breakage of pellets during pellet production of a polyamide composition containing an amorphous semi-aromatic polyamide and a crystalline polyamide. Provided are resin pellets, a method for producing the same, and a method for producing a polyamide composition using the polyamide resin pellets.

The inventors have made intensive studies to solve the above problems, and as a result, found that the above problems can be solved by setting the moisture content of the polyamide resin pellets to a specific range, and have completed the present invention. .

That is, the present invention includes the following aspects.
The polyamide resin pellets according to the first aspect of the present invention are polyamide resin pellets containing polyamide 6I , containing 90% by mass or more of the polyamide 6I with respect to the total mass of the polyamide resin pellets, and the polyamide resin pellets The moisture content relative to the total mass is 3200 ppm or more and 7500 ppm or less .

A production method according to a second aspect of the present invention is a method for producing a polyamide resin pellet according to the first aspect, comprising: a polymerization step of obtaining the polyamide 6I by polymerizing a dicarboxylic acid and a diamine; A pellet forming step of obtaining pellets of polyamide 6I by extruding the melt as a strand, cooling and cutting the extruded strand, and an adjusting step of adjusting the moisture content of the pellet to 3200 ppm or more and 7500 ppm or less; including.
The adjustment step may be a drying step or a dehydration step.

The polyamide composition according to the third aspect of the present invention comprises the polyamide resin pellets according to the first aspect as the amorphous semi-aromatic polyamide, polyamide 66 or polyamide 6 as the crystalline polyamide, and an inorganic filler, and glass fiber.

A method for producing a polyamide composition according to a fourth aspect of the present invention comprises the polyamide resin pellets according to the first aspect , polyamide 66 or polyamide 6 as a crystalline polyamide , and glass fiber as an inorganic filler. A melt-kneading step of melt-kneading the raw material components containing, and a pellet-forming step of obtaining pellets of the polyamide composition by extruding the melt-kneaded product obtained in the melt-kneading step as a strand and cooling and cutting the extruded strand and

According to the above aspect of the polyamide resin pellets and the method for producing the same, it is possible to suppress coloration of the pellets and strand breakage during pellet production of the polyamide composition containing the amorphous semi-aromatic polyamide and the crystalline polyamide. In the method for producing a polyamide composition according to the aspect described above, by using the polyamide resin pellets, coloration and strand breakage of the obtained polyamide composition pellets can be suppressed.

≪Polyamide resin pellet≫
The polyamide resin pellets of the present embodiment contain a polyamide composed of dicarboxylic acid units and diamine units.
In addition, the above polyamide contains 60 mol% or more of isophthalic acid units relative to the total molar amount of dicarboxylic acid units, and 50 linear aliphatic diamine units having 4 to 10 carbon atoms relative to the total molar amount of diamine units. Contains mol% or more.
Further, the polyamide resin pellets of the present embodiment contain 90% by mass or more of the above polyamide with respect to the total mass of the polyamide resin pellets.
In addition, the polyamide resin pellet of the present embodiment has a moisture content of 2500 ppm or more and 7500 ppm or less with respect to the total mass of the polyamide resin pellet.

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

The polyamide resin pellets of the present embodiment can suppress coloration and strand breakage during pellet production of a polyamide composition containing an amorphous semi-aromatic polyamide and a crystalline polyamide by having the above configuration.
The coloration of the pellets of the polyamide composition can be specifically evaluated, for example, by measuring the b value of the pellets of the polyamide composition with a color difference meter, as described in the examples below.

<Polyamide>
In the polyamide contained in the polyamide resin pellets of the present embodiment, the content of isophthalic acid units and linear aliphatic diamine units having 4 to 10 carbon atoms with respect to the total molar amount of dicarboxylic acid units and diamine units is 80 mol%. 100 mol % or less is preferable, 90 mol % or more and 100 mol % or less is more preferable, and 100 mol % is even more preferable.
In this specification, the ratio of each constitutional unit of the polyamide (units derived from predetermined monomers constituting the polyamide) can be measured by, for example, nuclear magnetic resonance spectroscopy (NMR).
Next, the details of each constituent unit of the polyamide will be described below.

[Dicarboxylic acid unit]
In the polyamide, the isophthalic acid unit is contained in an amount of 60 mol% or more, preferably 75 mol% or more and 100 mol% or less, more preferably 80 mol% or more and 100 mol% or less, based on the total molar amount of the dicarboxylic acid units, More preferably 90 mol % or more and 100 mol % or less, and particularly preferably 100 mol %.
In polyamide, the content of isophthalic acid units with respect to the total molar amount of dicarboxylic acid units is at least the above lower limit, so that mechanical properties, especially water absorption stiffness, stiffness under high temperature use (hereinafter referred to as "hot stiffness" It is possible to obtain a polyamide composition which simultaneously satisfies fluidity, surface appearance and the like.

Moreover, in polyamide, dicarboxylic acid units other than isophthalic acid units may be included as dicarboxylic acid units. Examples of dicarboxylic acid units other than isophthalic acid units include aromatic dicarboxylic acid units other than isophthalic acid units, aliphatic dicarboxylic acid units, and alicyclic dicarboxylic acid units.

(Aromatic dicarboxylic acid unit other than isophthalic acid unit)
Examples of aromatic dicarboxylic acids constituting aromatic dicarboxylic acid units other than isophthalic acid units include, but are not limited to, dicarboxylic acids having aromatic groups such as phenyl and naphthyl groups. The aromatic group of the aromatic dicarboxylic acid may be unsubstituted or may have a substituent.
Examples of substituents include, but are not limited to, alkyl groups having 1 to 4 carbon atoms, aryl groups having 6 to 10 carbon atoms, arylalkyl groups having 7 to 10 carbon atoms, halogen groups, and 1 or more carbon atoms. A silyl group of 6 or less, a sulfonic acid group, salts thereof, and the like. Halogen groups include, for example, a chloro group and a bromo group. Salts of sulfonic acid groups include sodium sulfonate groups and the like.
Specific examples of aromatic dicarboxylic acids other than isophthalic acid include, but are not limited to, terephthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, and 5-methylisophthalic acid. , 5-sodiumsulfoisophthalic acid, unsubstituted or substituted with a predetermined substituent and having 8 to 20 carbon atoms, and the like.
The aromatic dicarboxylic acids constituting the aromatic dicarboxylic acid unit may be used singly or in combination of two or more.

(aliphatic dicarboxylic acid unit)
The aliphatic dicarboxylic acid constituting the aliphatic dicarboxylic acid unit is not limited to the following, but examples include malonic acid, dimethylmalonic acid, succinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethyl Glutaric acid, 2,2-diethylsuccinic acid, 2,3-diethylglutaric acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, suberic acid, azelaine Linear or branched saturated aliphatic dicarboxylic acids having 3 to 20 carbon atoms such as acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, eicosanedioic acid, diglycolic acid, etc. be done.
The aliphatic dicarboxylic acid constituting the aliphatic dicarboxylic acid unit may be used alone or in combination of two or more.

(Alicyclic dicarboxylic acid unit)
The alicyclic dicarboxylic acid constituting the alicyclic dicarboxylic acid unit (hereinafter sometimes referred to as "alicyclic dicarboxylic acid unit") is not limited to the following, for example, 3 carbon atoms Among them, alicyclic dicarboxylic acids having an alicyclic structure having 10 or more carbon atoms are preferred.
Examples of such alicyclic dicarboxylic acids include, but are not limited to, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, and the like. be done. Among them, 1,4-cyclohexanedicarboxylic acid is preferred.
The alicyclic dicarboxylic acid constituting the alicyclic dicarboxylic acid unit may be used alone or in combination of two or more.

Also, the alicyclic group of the alicyclic dicarboxylic acid may be unsubstituted or may have a substituent. Examples of substituents include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl groups having 1 to 4 carbon atoms. Examples include the following alkyl groups.

Among them, the dicarboxylic acid unit other than the isophthalic acid unit is preferably an aromatic dicarboxylic acid unit, more preferably an aromatic dicarboxylic acid having 6 or more carbon atoms.
By using such a dicarboxylic acid, the polyamide composition tends to be more excellent in mechanical properties, particularly water absorption rigidity, heat rigidity, fluidity, surface appearance, and the like.

Moreover, the dicarboxylic acid constituting the dicarboxylic acid unit is not limited to the compounds described as the above dicarboxylic acids, and compounds equivalent to the above dicarboxylic acids may be used.
Here, the term "a compound equivalent to a dicarboxylic acid" refers to a compound capable of becoming a dicarboxylic acid unit similar to the dicarboxylic acid unit derived from the above dicarboxylic acid. Examples of such compounds include, but are not limited to, anhydrides and halides of dicarboxylic acids.

(Trivalent or higher polyvalent carboxylic acid unit)
In addition, the polyamide may further contain a trivalent or higher polyvalent carboxylic acid unit such as trimellitic acid, trimesic acid, pyromellitic acid, etc., if necessary.
The trivalent or higher polyvalent carboxylic acid may be used alone or in combination of two or more.

[Diamine unit]
The polyamide contains 50 mol % or more of chain aliphatic diamine units having 4 to 10 carbon atoms relative to the total molar amount of diamine units.
Chain aliphatic diamine units having 4 to 10 carbon atoms are not limited to the following, but examples include tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, and nonamethylene. Straight-chain saturated aliphatic diamines having 4 to 10 carbon atoms such as diamine and decamethylenediamine are included.
Among them, the chain aliphatic diamine unit having 4 to 10 carbon atoms is preferably a diamine unit having a linear saturated aliphatic group having 4 to 10 carbon atoms, and a linear saturated diamine having 6 to 10 carbon atoms. A diamine unit having an aliphatic group is more preferred, and a hexamethylenediamine unit is even more preferred.
When the polyamide has such a diamine unit, the polyamide composition tends to be more excellent in mechanical properties, particularly water absorption stiffness, heat stiffness, fluidity, surface appearance, and the like.

Moreover, in polyamide, a diamine unit other than a chain aliphatic diamine unit having 4 to 10 carbon atoms may be included as a diamine unit. Examples of diamine units other than chain aliphatic diamine units having 4 to 10 carbon atoms include, but are not limited to, aliphatic diamine units other than chain aliphatic diamine units having 4 to 10 carbon atoms. group diamine units, alicyclic diamine units, aromatic diamine units, and the like.

(Aliphatic diamine units other than chain aliphatic diamine units having 4 to 10 carbon atoms)
Aliphatic diamines constituting aliphatic diamine units other than chain aliphatic diamine units having 4 to 10 carbon atoms are not limited to the following, for example, ethylenediamine, propylenediamine, undecamethylenediamine, Linear saturated aliphatic diamines having 2 or more and 3 or less carbon atoms and 11 or more and 20 or less carbon atoms such as dodecamethylenediamine and tridecamethylenediamine are exemplified.
The aliphatic diamines constituting the aliphatic diamine acid unit may be used singly or in combination of two or more.

(alicyclic diamine unit)
The alicyclic diamine (hereinafter sometimes referred to as "alicyclic diamine") constituting the alicyclic diamine unit is not limited to the following, but examples include 1,4-cyclohexanediamine, 1 ,3-cyclohexanediamine, 1,3-cyclopentanediamine and the like.
The alicyclic diamines constituting the alicyclic diamine acid unit may be used singly or in combination of two or more.

(aromatic diamine unit)
The aromatic diamine constituting the aromatic diamine unit is not limited to the following as long as it is a diamine containing an aromatic group, and examples thereof include meta-xylylenediamine.
The aromatic diamines constituting the aromatic diamine acid unit may be used singly or in combination of two or more.

(Trivalent or higher polyvalent aliphatic amine unit)
In addition, the polyamide may further contain trivalent or higher polyvalent aliphatic amine units such as bishexamethylenetriamine, if necessary.
The trivalent or higher polyvalent aliphatic amine units may be used singly or in combination of two or more.

[Preferred example of polyamide]
The polyamide contained in the polyamide resin pellets of the present embodiment is preferably polyamide 6I, 9I, or 10I, and more preferably polyamide 6I.

[Polymer end of polyamide]
Polyamide polymer ends are not particularly limited, but can be classified and defined as follows.
2) carboxyl terminus; 3) capped terminus; 4) other terminus.
1) Amino terminus is a polymer terminus having an amino group ( _--NH2 group) and is derived from the starting diamine unit.
2) The carboxyl terminal is a polymer terminal having a carboxyl group (--COOH group), which is derived from the starting dicarboxylic acid.
3) Terminals formed by a capping agent are terminals formed when a capping agent is added during polymerization. The terminal blocking agent mentioned above is mentioned as a blocking agent.
4) Other terminals are polymer terminals not classified in 1) to 3) above, and include terminals generated by deammonification reaction of amino terminals, terminals generated by decarboxylation reaction of carboxyl terminals, and the like. .

[Terminal blocking agent]
The ends of the polyamide may be end-blocked with a known end-blocking agent.
Such a terminal blocking agent can also be added as a molecular weight modifier when producing a polyamide from the dicarboxylic acid and the diamine.
Also, a polyamide composition containing a polyamide whose ends are blocked with a terminal blocking agent tends to be superior in heat resistance, fluidity, toughness, low water absorption, and rigidity.

Examples of terminal blocking agents include, but are not limited to, monocarboxylic acids, monoamines, acid anhydrides, monoisocyanates, monoacid halides, monoesters, and monoalcohols. Examples of acid anhydrides include phthalic anhydride and the like.
Among them, a monocarboxylic acid or a monoamine is preferable as the terminal blocking agent. By blocking the ends of the polyamide with a terminal blocking agent, the polyamide composition tends to be more excellent in thermal stability.
Only one type of terminal blocker may be used alone, or two or more types may be used in combination.

The monocarboxylic acid that can be used as a terminal blocker may have reactivity with an amino group that may be present at the terminal of the polyamide, and is not limited to the following, for example, aliphatic monocarboxylic acid acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids, and the like. Examples of aliphatic monocarboxylic acids include formic acid, 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 isobutyric acid. mentioned. Examples of alicyclic monocarboxylic acids include cyclohexanecarboxylic acid and the like. Examples of aromatic monocarboxylic acids include benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid.
Monocarboxylic acids may be used alone or in combination of two or more.

The monoamine that can be used as a terminal blocking agent is not limited to the following, as long as it has reactivity with the carboxyl group that may be present at the end of the polyamide. For example, aliphatic monoamine, alicyclic monoamines, aromatic monoamines, and the like. Examples of aliphatic monoamino include methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine and dibutylamine. Alicyclic monoamines include, for example, cyclohexylamine and dicyclohexylamine. Examples of aromatic monoamines include aniline, toluidine, diphenylamine, naphthylamine and the like.
Monoamines may be used alone or in combination of two or more.

[Physical properties of polyamide]
(Polyamide crystallization enthalpy ΔH)
The heat of fusion (enthalpy of crystallization ΔH) of the polyamide measured at 20° C./min with a differential scanning calorimeter is preferably less than 4 J/g from the viewpoint of mechanical properties, particularly water absorption stiffness and hot stiffness. That is, the polyamide contained in the polyamide resin pellets of the present embodiment is preferably amorphous polyamide.
Examples of a device for measuring the crystallization enthalpy ΔH of polyamide include Diamond-DSC manufactured by PERKIN-ELMER.

[Polyamide content]
The polyamide content in the polyamide resin pellets of the present embodiment is 90% by mass or more, preferably 95% by mass or more, more preferably 99% by mass or more, relative to the total mass of the polyamide resin pellets. When the content of the polyamide is equal to or higher than the above lower limit, the content of contaminants such as reaction by-products generated during polyamide production is further reduced, and the effect of the polyamide resin pellets of the present embodiment is achieved. It can be exhibited more prominently.

<Method for producing polyamide resin pellets>
The polyamide resin pellets of the present embodiment can be produced, for example, by a method including a polymerization step, a pellet forming step, and a drying step.
In the polymerization step, a dicarboxylic acid and a diamine are polymerized to obtain the polyamide.
In the pellet forming step, the polyamide melt is extruded as a strand, and the extruded strand is cooled and cut to obtain polyamide pellets.
In the drying step, the pellets are dried. Also, by adjusting the temperature or time in the drying process, the moisture content of the pellets can be adjusted to 2500 ppm or more and 7500 ppm or less.

Alternatively, the polyamide resin pellets of the present embodiment include, for example, a polymerization step and a pellet forming step, and after the pellet forming step, a method that does not substantially include a drying step. can be done. The polymerization step, pellet forming step and drying step referred to here are steps in which the same operations as those described in the above manufacturing method are performed. Further, the term "substantially not including a drying process" as used herein means that no drying process is performed at all, or that drying is performed only to such an extent that the moisture content of the polyamide resin pellets does not change.

The moisture content of polyamide resin pellets depends on the length of time the strands are immersed in water when they are cooled, the presence or absence of a dehydration process in which the pellets obtained by cutting the strands are dehydrated by centrifugation, and the drying of the pellets obtained by cutting the strands. It can be adjusted by adjusting the presence or absence of a drying step, and adjusting the drying temperature and time of the pellets.
For example, when increasing the moisture content of the polyamide resin pellets, for example, lengthen the water immersion time, do not perform the dehydration step of dehydrating the pellets, and lower the rotation speed of the centrifuge in the dehydration step. , shortening the dehydration time, not performing the drying step, lowering the drying temperature, and shortening the drying time.
Next, each step of the method for producing polyamide resin pellets of the present embodiment will be described in detail below.

[Polymerization step]
In the polymerization step, the amount of dicarboxylic acid added and the amount of diamine added are preferably about the same molar amount. Considering the amount of diamine that escapes to the outside of the reaction system during the polymerization reaction, the molar ratio of the total diamine is 0.9 or more and 1.2 or less with respect to the total molar amount of the dicarboxylic acid of 1. , more preferably 0.95 or more and 1.1 or less, and even more preferably 0.98 or more and 1.05 or less.
The polymerization method is not limited to the following, but for example, a dicarboxylic acid that constitutes a dicarboxylic acid unit, a diamine that constitutes a diamine unit, and optionally at least one of a lactam unit and an aminocarboxylic acid unit. and a method of obtaining a polymer by polymerizing at least one selected from the group consisting of lactams and aminocarboxylic acids constituting either one.
Moreover, it is preferable that the polymerization step further includes a degree of polymerization increasing step for increasing the degree of polymerization of the polyamide. Moreover, in the polymerization step, if necessary, a blocking step of blocking the ends of the obtained polymer with a terminal blocking agent may be included.

Specific polymerization methods include, for example, various methods as exemplified below.
1) A method of heating a dicarboxylic acid-diamine salt, an aqueous solution of a mixture of a dicarboxylic acid and a diamine, or a suspension of these in water and polymerizing them while maintaining the molten state (hereinafter referred to as “thermal melt polymerization (sometimes referred to as “lawful”).
2) A method of increasing the degree of polymerization of a polyamide obtained by hot melt polymerization while maintaining the solid state at a temperature below the melting point (hereinafter sometimes referred to as "hot melt polymerization and solid state polymerization").
3) A method of polymerizing a dicarboxylic acid-diamine salt or a mixture of a dicarboxylic acid and a diamine while maintaining the solid state (hereinafter sometimes referred to as "solid phase polymerization method").
4) A method of polymerizing using a dicarboxylic acid halide component and a diamine component equivalent to the dicarboxylic acid (hereinafter sometimes referred to as "solution method").

Among them, a polymerization method including a hot melt polymerization method is preferable, and when producing a polyamide by a hot melt polymerization method, it is preferable to maintain a molten state until the polymerization is completed. As a method for maintaining the molten state, production may be performed under polymerization conditions suitable for the composition of the polyamide. For example, the polymerization pressure in the hot melt polymerization method is controlled to 14 kg/cm ² or more and 25 kg/cm ² or less (gauge pressure), and the pressure in the tank reaches atmospheric pressure (gauge pressure is 0 kg/cm ² ) while continuing heating. A method of lowering the blood pressure over 30 minutes or more until it becomes

The mode of polymerization is not particularly limited, and may be a batch system or a continuous system.
The polymerization apparatus is not particularly limited, and known apparatuses can be used. Examples thereof include an autoclave reactor, a tumbler reactor, and an extruder reactor such as a kneader.

Hereinafter, as a polymerization method, a method for producing a polyamide by a batch-type hot-melt polymerization method will be specifically described, but the polymerization method is not limited to this.
First, for example, an aqueous solution containing about 40% by mass or more and 60% by mass or less of polyamide raw material components (dicarboxylic acid, diamine, and, if necessary, at least one of lactam and aminocarboxylic acid), In a concentration tank operated at a temperature of 110 ° C. or higher and 180 ° C. or lower and a pressure of about 0.035 MPa or higher and 0.6 MPa or lower (gauge pressure), the concentrated solution is concentrated to about 65% by mass or higher and 90% by mass or lower. obtain.
The resulting concentrated solution is then transferred to an autoclave and heating is continued until the pressure in the autoclave is about 1.2 MPa to 2.2 MPa (gauge pressure).
After that, in the autoclave, the pressure is maintained at about 1.2 MPa or more and 2.2 MPa or less (gauge pressure) while removing at least one of water and gas components, and when the temperature reaches about 220 ° C. or more and 260 ° C. or less , the pressure is lowered to atmospheric pressure (gauge pressure is 0 MPa).
By reducing the pressure in the autoclave to atmospheric pressure and then reducing the pressure as necessary, water produced as a by-product can be effectively removed.

[Pellet forming process]
The polyamide obtained after the polymerization step is placed in a reactor such as an autoclave, pressurized with an inert gas such as nitrogen, and extruded as a strand from the autoclave as a melted polyamide. Pellets of polyamide are obtained by cooling and cutting the extruded strands. At this time, the moisture content of the polyamide resin pellets can be adjusted within the above range by appropriately adjusting the water immersion time when the strands are cooled.

[Drying process]
The pellets obtained after the pelletizing step are dried. As described above, when the moisture content of the polyamide resin pellets is already within the above range, the drying process may not be performed.
As the drying temperature and drying time, the temperature and time can be set so that the moisture content of the polyamide resin pellets can be adjusted within the above range. Specifically, the moisture content of the polyamide resin pellets can be adjusted within the above range by drying the pellets at a temperature of about 60° C. or higher and 100° C. or lower, for example, for about 1 hour or more and 12 hours or less.

[Other processes]
The method for producing polyamide resin pellets of the present embodiment may include other steps in addition to the polymerization step, the pellet forming step, and the drying step. Other steps include, for example, a dehydration step.
The dehydration step can be performed after the pellet forming step and before the drying step. Specifically, in the dehydration step, the pellet is dehydrated using, for example, a centrifuge or the like. By appropriately adjusting the dehydration time and the rotation speed of the centrifuge, the moisture content of the polyamide resin pellets can be adjusted within the above range.

<Characteristics of polyamide resin pellets>
Specifically, the weight-average molecular weight Mw (A) and moisture content, which are the properties of the polyamide resin pellets, can be measured by the methods described in Examples below.

[Weight average molecular weight Mw (A)]
The weight average molecular weight Mw (A) can be used as an index of the molecular weight of the polyamide resin pellets. The weight-average molecular weight Mw(A) can be measured using gel permeation chromatography (GPC) as described later in Examples.

[Moisture content]
The moisture content of the polyamide resin pellets is 2500 ppm or more and 7500 ppm or less, preferably 3000 ppm or more and 7000 ppm or less, and more preferably 4000 ppm or more and 6000 ppm or less.
When the moisture content of the polyamide resin pellets is equal to or higher than the above lower limit, the coloring of the pellets of the polyamide composition is more effectively achieved when producing the pellets of the polyamide composition containing the polyamide resin pellets and the crystalline polyamide. can be suppressed.
When the moisture content of the polyamide resin pellets is equal to or less than the above upper limit, when producing pellets of a polyamide composition containing polyamide resin pellets and crystalline polyamide, strand breakage during extrusion is more effectively prevented. be able to.
As a method of controlling the moisture content of the polyamide resin pellets within the above range, a method of cooling with water during the production of the polyamide resin pellets and adjusting the cooling time, or adjusting the drying temperature and time after pelletization. method.
The moisture content of the polyamide resin pellets can be measured, for example, using a Karl Fischer moisture meter, as described in Examples below.

<<Method for producing polyamide composition>>
The polyamide composition of the present embodiment contains (A) polyamide resin pellets and (B) crystalline polyamide, and can be produced, for example, by a method including a melt kneading step and a pellet forming step.

In the method for producing a polyamide composition of the present embodiment, by using the above-mentioned (A) polyamide resin pellets, it is possible to suppress coloration and strand breakage of the obtained polyamide composition pellets.
Each step of the method for producing the polyamide composition of the present embodiment will be described in detail below.

<Manufacturing process>
[Melting kneading process]
In the melt-kneading step, raw material components including (A) polyamide resin pellets and (B) crystalline polyamide are melt-kneaded in an extruder. It is preferable to set the temperature of the extruder to the melting peak temperature Tm2+30° C. or less of the polyamide composition to be obtained.

(A) The amount of the polyamide resin pellets can be 5.0% by mass or more and 50.0% by mass or less with respect to the total mass of the resin contained in the resulting polyamide composition, and 10.0% by mass. 45.0% by mass or less is preferable, 15.0% by mass or more and 40.0% by mass or less is more preferable, 20.0% by mass or more and 37.5% by mass or less is even more preferable, and 22.5% by mass or more and 35.0% by mass or less is preferable. 0% by mass or less is particularly preferable, and 22.5% by mass or more and 30.0% by mass or less is most preferable. By setting the blending amount of the polyamide resin pellets within the above range, it is possible to more effectively suppress the decrease in the molecular weight of the polyamide composition due to the moisture content of the (A) polyamide resin pellets.

As a method of melt-kneading raw material components containing the above (A) polyamide resin pellets and (B) crystalline polyamide, for example, (A) polyamide resin pellets, (B) crystalline polyamide, and other raw materials A method of mixing using a tumbler, Henschel mixer, etc., supplying to a melt kneader and kneading, or (A) polyamide resin pellets and (B) crystalline polyamide in a molten state with a single-screw or twin-screw extruder , a method of blending other raw materials from a side feeder, and the like.
As for the method of supplying the components constituting the polyamide composition to the melt kneader, all the components may be supplied to the same supply port at once, or the components may be supplied from different supply ports.

The melt-kneading temperature is preferably about 250° C. or higher and 350° C. or lower in terms of resin temperature.
The melt-kneading time is preferably about 0.25 minutes or more and 5 minutes or less.
The apparatus for melt-kneading is not particularly limited, and known apparatuses such as single-screw or twin-screw extruders, Banbury mixers, mixing rolls, and other melt-kneaders can be used.

[Pellet forming process]
In the pellet forming step, the same operation as described in the “pellet forming step” in the above “method for producing polyamide resin pellets” can be performed. By using the polyamide resin pellets (A), it is possible to suppress the coloring and strand breakage of the pellets of the obtained polyamide composition in the pellet forming step.

[Other processes]
The method for producing the polyamide composition of the present embodiment may include other steps in addition to the melt kneading step and the pellet forming step. Other processes include, for example, a dehydration process, a drying process, and the like.
The dehydration step can be performed after the pellet formation step, and the obtained pellets are dehydrated using a centrifuge or the like. The dehydration time, the number of revolutions of the centrifuge, and the like can be appropriately adjusted according to the intended use of the polyamide composition.
A drying step can be performed after the pellet forming step or the dehydrating step, and the obtained pellets are dried. The drying temperature and drying time can be appropriately adjusted according to the intended use of the polyamide composition.

<Constituent Components of Polyamide Composition>
The polyamide composition obtained by the production method of the present embodiment contains the above (A) polyamide resin pellets and (B) crystalline polyamide.

[(B) Crystalline Polyamide]
As used herein, the term “crystalline polyamide” refers to a polyamide having a heat of fusion of crystals (enthalpy of crystallization ΔH) of 4 J/g or more when measured at 20° C./min with a differential scanning calorimeter.
Specific examples of the (B) crystalline polyamide include, but are not limited to, (Ba) a polyamide obtained by ring-opening polymerization of a lactam, and (Bb) a polyamide obtained by self-condensation of ω-aminocarboxylic acid. (Bc) a polyamide obtained by condensing a diamine and a dicarboxylic acid, a copolymer thereof, and the like. The crystalline polyamide may be used singly or as a mixture of two or more.

Examples of the lactam used in the (Ba) polyamide include, but are not limited to, pyrrolidone, caprolactam, undecalactam, dodecalactam, and the like.
The ω-aminocarboxylic acid used in the (Bb) polyamide is not limited to the following, but includes, for example, ω-amino fatty acids, which are ring-opening compounds of the above lactams with water.
The lactam or ω-aminocarboxylic acid may be condensed individually, or two or more monomers may be condensed together.

The diamine (monomer) used in the above (Bc) polyamide is not limited to the following, but examples include linear saturated aliphatic diamines, branched saturated aliphatic diamines, aromatic diamines, and alicyclic diamines. etc. Examples of linear saturated aliphatic diamines include hexamethylenediamine and pentamethylenediamine. Branched saturated aliphatic diamines include, for example, 2-methylpentanediamine and 2-ethylhexamethylenediamine. Examples of aromatic diamines include p-phenylenediamine and m-phenylenediamine. cyclohexanediamine, cyclopentanediamine, cyclooctanediamine and the like.
The dicarboxylic acid (monomer) used in the (Bc) polyamide is not limited to the following, and examples thereof include aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and alicyclic dicarboxylic acids. Examples of aliphatic dicarboxylic acids include adipic acid, pimelic acid, sebacic acid and the like. Examples of aromatic dicarboxylic acids include phthalic acid and isophthalic acid. Alicyclic dicarboxylic acids include, for example, cyclohexanedicarboxylic acid.
The diamine and dicarboxylic acid as the monomers described above may be condensed singly or in combination of two or more monomers.

In addition, (B) the crystalline polyamide may further contain polyvalent carboxylic acid units having a valence of 3 or more, such as trimellitic acid, trimesic acid, pyromellitic acid, etc., if necessary. The trivalent or higher polyvalent carboxylic acid may be used alone or in combination of two or more.

(Preferred example of (B) crystalline polyamide)
(B) As crystalline polyamides, specifically, polyamide 4 (polyα-pyrrolidone), polyamide 6 (polycaproamide), polyamide 11 (polyundecaneamide), polyamide 12 (polydodecanamide), polyamide 46 (poly tetramethylene adipamide), polyamide 56 (polypentamethylene adipamide), polyamide 66 (polyhexamethylene adipamide), polyamide 610 (polyhexamethylene sebacamide), polyamide 612 (polyhexamethylene dodecamide), Examples include polyamide 6T (polyhexamethylene terephthalamide), polyamide 9T (polynonanemethylene terephthalamide), and copolymer polyamides containing these as constituents.
Among them, polyamide 66 (PA66), polyamide 6 (PA6), polyamide 610 (PA610), or polyamide 612 (PA612) is preferable as the (B) crystalline polyamide. PA66 is a material suitable for automobile parts because of its excellent heat resistance, moldability and toughness. In addition, long-chain aliphatic polyamides such as PA610 are excellent in chemical resistance.

((B) Weight average molecular weight of crystalline polyamide)
(B) The weight average molecular weight Mw (B) can be used as an index of the molecular weight of the crystalline polyamide. The weight-average molecular weight Mw(B) can be measured using GPC as described later in Examples.

In addition to the (A) polyamide resin pellets and the (B) crystalline polyamide, the polyamide composition obtained by the production method of the present embodiment includes (C) an inorganic filler, (D) a nucleating agent, and (E) Lubricants, (F) stabilizers, (G) other polymers, (H) at least one selected from the group consisting of metal phosphites and metal hypophosphites, and (I) phosphites It may contain one or more components selected from the group consisting of compounds.

[(C) inorganic filler]
(C) Inorganic fillers include, but are not limited to, glass fibers, carbon fibers, calcium silicate fibers, potassium titanate fibers, aluminum borate fibers, clay, glass flakes, talc, Kaolin, mica, hydrotalcite, calcium carbonate, magnesium 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, montmorillonite, swelling fluoromica , apatite and the like. These (C) inorganic fillers may be used singly or in combination of two or more.
Among them, from the viewpoint of further improving mechanical strength, from the group consisting of glass fiber, carbon fiber, wollastonite, kaolin, mica, talc, calcium carbonate, magnesium carbonate, potassium titanate fiber, aluminum borate fiber and clay One or more selected are preferred. Among them, more preferably one or more selected from the group consisting of glass fiber, carbon fiber, wollastonite, kaolin, mica, talc, calcium carbonate and clay.

(C) When the inorganic filler is glass fiber or carbon fiber, the number average fiber diameter (d) is preferably 3 μm or more and 30 μm or less, more preferably 3 μm or more and 20 μm or less, further preferably 3 μm or more and 12 μm or less, and 3 μm or more and 9 μm. The following are particularly preferable, and 4 μm or more and 6 μm or less are most preferable.
By setting the number average fiber diameter to the above upper limit or less, it is possible to obtain a polyamide composition having excellent toughness and surface appearance of molded articles. On the other hand, by setting the number-average fiber diameter to the above lower limit or more, a polyamide composition having excellent balance between cost, powder handling, and physical properties (fluidity, etc.) can be obtained. Furthermore, by setting the number average fiber diameter to 3 μm or more and 9 μm or less, it is possible to obtain a polyamide composition having excellent vibration fatigue properties and slidability.

(C) When the inorganic filler is glass fiber or carbon fiber, its cross section may be circular or flat. Examples of such a flattened cross-section include, but are not limited to, a rectangular shape, an oval shape close to a rectangle, an elliptical shape, and a cocoon shape with a constricted central portion in the longitudinal direction. Here, the "flatness ratio" in the present specification refers to a value represented by d2/d1, where d2 is the major axis of the fiber cross section and d1 is the minor axis of the fiber cross section (perfect circle means flattened ratio is about 1).

(C) When the inorganic filler is glass fiber or carbon fiber, the number average fiber diameter (d) is 3 μm or more and 30 μm or less from the viewpoint of imparting excellent mechanical strength to the polyamide composition, and the weight average The fiber length (l) is 100 μm or more and 750 μm or less, and the ratio of the number average fiber diameter (d) to the weight average fiber length (l), that is, the aspect ratio (l/d) is 10 or more and 100 or less. is preferred. The "number average fiber diameter (d)" referred to here is the average value of the length of the fiber cross section (d2 above), and is obtained using the calculation method described later.

In addition, from the viewpoint of reducing warpage of the plate-shaped molded product and improving heat resistance, toughness, low water absorption, and heat aging resistance, the flatness is preferably 1.5 or more, and 1.5 or more and 10.0. The following is more preferable, 2.5 or more and 10.0 or less is still more preferable, more than 3.0 or more and 6.0 or less is particularly preferable, and 3.1 or more and 6.0 or less is most preferable. When the flatness is within the above range, crushing can be more effectively prevented during processing such as mixing with other components, kneading and molding, and the desired effect for the molded product can be obtained more sufficiently. become.

The thickness of the glass fiber or carbon fiber having an oblateness of 1.5 or more is not limited to the following, but the short diameter d1 of the fiber cross section is 0.5 μm or more and 25 μm or less and the long diameter d2 of the fiber cross section is 1.25 μm or more. It is preferably 250 μm or less. More preferably, the minor axis d1 of the fiber cross section is 3.0 μm or more and 25 μm or less, and the major axis d2 of the fiber cross section is 1.25 μm or more and 250 μm or less. When the short diameter (d1) and long diameter (d2) are within the above ranges, the difficulty of fiber spinning can be more effectively avoided, and the strength of the molded product is improved without reducing the contact area with the resin (polyamide). can be further improved.

Glass fibers and carbon fibers with a flatness of 1.5 or more are, for example, Japanese Patent Publication No. 3-059019 (reference material 1), Japanese Patent Publication No. 4-013300 (reference material 2), Japanese Patent Publication No. 4-032775. It can be produced using the method described in (Reference Material 3) and the like. In particular, an orifice plate having a number of orifices on its bottom surface, the orifice plate having a convex rim surrounding a plurality of orifice outlets and extending downwardly from the bottom surface, or the outer periphery of a nozzle tip having one or more orifice holes. Glass fibers having an oblateness of 1.5 or greater produced using any modified cross-section glass fiber spinning nozzle tip with a plurality of convex edges extending downwardly from the tip are preferred. These fibrous reinforcing materials may be used as they are as roving fiber strands, or may be further subjected to a cutting process and used as chopped glass strands.

Also, the "number average fiber diameter (d)" and "weight average fiber length (l)" in the present specification can be obtained by the following methods. First, the polyamide composition is placed in an electric furnace to incinerate the contained organic matter. 100 or more glass fibers (or carbon fibers) are arbitrarily selected from the residue after the treatment, observed with a scanning electron microscope (SEM), and the fiber diameter (major diameter) of these glass fibers (or carbon fibers) ), the number average fiber diameter can be determined. In addition, the weight average fiber length can be obtained by measuring the fiber length using SEM photographs of the 100 or more glass fibers (or carbon fibers) taken at a magnification of 1000 times.

Also, the glass fiber or carbon fiber may be surface-treated with a silane coupling agent or the like.
Examples of silane coupling agents include, but are not limited to, aminosilanes, mercaptosilanes, epoxysilanes, vinylsilanes, and the like.
Examples of aminosilanes include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane and the like.
Mercaptosilanes include, for example, γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane.
These silane coupling agents may be used alone or in combination of two or more.
Among them, aminosilanes are preferable as the silane coupling agent.

Also, the glass fiber or carbon fiber may further contain a sizing agent.
Examples of the sizing agent include copolymers and epoxy compounds containing, as structural units, a carboxylic anhydride-containing unsaturated vinyl monomer and an unsaturated vinyl monomer other than the carboxylic anhydride-containing unsaturated vinyl monomer. , polyurethane resins, homopolymers of acrylic acid, copolymers of acrylic acid and other copolymerizable monomers, and salts of these with primary, secondary and tertiary amines. These sizing agents may be used alone or in combination of two or more.
Among them, from the viewpoint of the mechanical strength of the resulting polyamide composition, as a sizing agent, an unsaturated vinyl monomer other than a carboxylic acid anhydride-containing unsaturated vinyl monomer and a carboxylic acid anhydride-containing unsaturated vinyl monomer At least one selected from the group consisting of copolymers, epoxy compounds, and polyurethane resins, each containing as a structural unit, is preferred. Further, it is selected from the group consisting of copolymers and polyurethane resins containing, as structural units, unsaturated vinyl monomers containing carboxylic acid anhydride and unsaturated vinyl monomers other than unsaturated vinyl monomers containing carboxylic acid anhydride. more preferably one or more.

Glass fibers or carbon fibers are produced by applying the above-mentioned sizing agent to the fibers using a known method such as a roller applicator in the known manufacturing process of the fibers, and drying the produced fiber strands. obtained by a reactive reaction.
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 about 0.2% to 3% by mass with respect to the total mass of the glass fiber or carbon fiber, and 0.3% to 2% by mass. It is more preferable to give (add) the following degree.
When the addition amount of the sizing agent is equal to or more than the above lower limit as a solid content rate with respect to the total mass of the glass fibers or carbon fibers, the sizing of the fibers can be maintained more effectively. On the other hand, when the amount of the sizing agent added is not more than the above upper limit mass% as a solid content with respect to the total mass of the glass fibers or carbon fibers, the thermal stability of the obtained polyamide composition is further improved.
The strand may be dried after the cutting step, or the strand may be cut after drying.

Inorganic fillers other than glass fiber and carbon fiber include wollastonite, kaolin, mica, talc, calcium carbonate, magnesium carbonate, potassium titanate fiber, and boron, from the viewpoint of improving the strength, rigidity and surface appearance of molded products. Aluminum acid fibers or clay are preferred. Wollastonite, kaolin, mica, talc, calcium carbonate or clay are more preferred. Wollastonite, kaolin, mica or talc are more preferred. Wollastonite, mica or talc are particularly preferred. These inorganic fillers may be used individually by 1 type, and may be used in combination of 2 or more type.

The average particle size of the inorganic filler other than glass fiber and carbon fiber is preferably 0.01 μm or more and 38 μm or less, more preferably 0.03 μm or more and 30 μm or less, from the viewpoint of improving the toughness and the surface appearance of the molded product. It is more preferably 0.05 μm or more and 25 μm or less, even more preferably 0.10 μm or more and 20 μm or less, and particularly preferably 0.15 μm or more and 15 μm or less.
By setting the average particle diameter of the inorganic filler other than the glass fiber and the carbon fiber to the upper limit value or less, the polyamide composition can have excellent toughness and surface appearance of the molded product. On the other hand, by setting the average particle diameter to the above lower limit or more, a polyamide composition having an excellent balance between cost, powder handling, and physical properties (fluidity, etc.) can be obtained.

For acicular inorganic fillers such as wollastonite other than glass fiber and carbon fiber, the number average particle size (hereinafter sometimes simply referred to as "average particle size") is used as the average particle size. If the cross section is not a circle, the maximum length is taken as the (number average) fiber diameter.

Regarding the number average particle length of the needle-shaped inorganic filler (hereinafter sometimes simply referred to as "average particle length"), the preferred range of the number average particle size described above and the number average particle size (d) below A numerical range calculated from a preferred range of the aspect ratio (l/d) of the number average particle length (l) to is preferable.

Although it has a needle-like shape, the aspect ratio (l/d) of the number average particle length (l) to the number average particle diameter (d) improves the surface appearance of the molded product, and is suitable for injection molding machines and the like. From the viewpoint of preventing abrasion of metal parts, it is preferably 1.5 or more and 10 or less, more preferably 2.0 or more and 5 or less, and even more preferably 2.5 or more and 4 or less.

Inorganic fillers other than glass fiber and carbon fiber may be subjected to surface treatment using a silane coupling agent, a titanate-based coupling agent, or the like.
Examples of the silane coupling agent include those exemplified for the above glass fiber and carbon fiber.
Among them, aminosilanes are preferable as the silane coupling agent.
Such a surface treatment agent may be applied to the surface of the inorganic filler in advance, or may be added when the polyamide and the inorganic filler are mixed. Moreover, the addition amount of the surface treatment agent is preferably 0.05% by mass or more and 1.5% by mass or less with respect to the total mass of the inorganic filler.

(C) The content of the inorganic filler is preferably 5 parts by mass or more and 250 parts by mass or less, and 30 parts by mass or more and 250 parts by mass with respect to a total of 100 parts by mass of (A) polyamide resin pellets and (B) crystalline amide. 50 to 240 parts by mass is more preferable, 50 to 200 parts by mass is particularly preferable, and 50 to 150 parts by mass is most preferable.
(C) The content of the inorganic filler, with respect to a total of 100 parts by mass of (A) polyamide resin pellets and (B) crystalline amide, is at least the above lower limit, thereby obtaining strength and The effect of further improving rigidity is exhibited. On the other hand, the content of the (C) inorganic filler is set to the above upper limit or less with respect to a total of 100 parts by mass of the (A) polyamide resin pellets and (B) the crystalline amide, thereby improving the extrudability and moldability Excellent polyamide compositions can be obtained.

[(D) Nucleating agent]
(D) The nucleating agent means a substance that can provide at least one of the following effects (1) to (3) when added.
(1) Effect of raising the crystallization peak temperature of the polyamide composition.
(2) The effect of reducing the difference between the extrapolation start temperature and the extrapolation end temperature of the crystallization peak.
(3) Effect of refining the spherulites of the resulting molded product or uniformizing the size thereof.

(D) Nucleating agents include, but are not limited to, talc, boron nitride, mica, kaolin, silicon nitride, carbon black, potassium titanate, molybdenum disulfide, and the like.
(D) The nucleating agent may be used alone or in combination of two or more.
Among them, (D) the nucleating agent is preferably talc or boron nitride from the viewpoint of the effect of the nucleating agent.

Further, since the effect of the nucleating agent is high, the number average particle diameter of the nucleating agent (D) is preferably 0.01 μm or more and 10 μm or less.
The number average particle size of the nucleating agent can be measured using the following method. First, the molded article is dissolved in a solvent such as formic acid in which polyamide is soluble. Then, for example, 100 or more nucleating agents are arbitrarily selected from the obtained insoluble components. Then, it can be obtained by observing with an optical microscope, a scanning electron microscope, or the like and measuring the particle size.

[(E) Lubricant]
(E) Lubricants include, but are not limited to, higher fatty acids, higher fatty acid metal salts, higher fatty acid esters, higher fatty acid amides, and the like.

(higher fatty acid)
Examples of higher fatty acids include linear or branched saturated or unsaturated aliphatic monocarboxylic acids having 8 to 40 carbon atoms.
Examples of linear or branched saturated or unsaturated aliphatic monocarboxylic acids having 8 to 40 carbon atoms include lauric acid, palmitic acid, stearic acid, behenic acid and montanic acid.
Examples of branched saturated aliphatic monocarboxylic acids having 8 to 40 carbon atoms include isopalmitic acid and isostearic acid.
Examples of linear unsaturated aliphatic monocarboxylic acids having 8 to 40 carbon atoms include oleic acid and erucic acid.
Examples of branched unsaturated aliphatic monocarboxylic acids having 8 to 40 carbon atoms include isoleic acid.
Among them, stearic acid or montanic acid is preferable as the higher fatty acid.

(Higher fatty acid metal salt)
A higher fatty acid metal salt is a metal salt of a higher fatty acid.
Examples of the metal elements of the metal salt include Group 1 elements, Group 2 elements and Group 3 elements of the periodic table of elements, zinc, aluminum and the like.
Group 1 elements of the periodic table of elements include, for example, sodium and potassium.
Group 2 elements of the periodic table of elements include, for example, calcium and magnesium.
Group 3 elements of the periodic table of elements include, for example, scandium and yttrium.
Among them, elements of groups 1 and 2 of the periodic table or aluminum are preferable, and sodium, potassium, calcium, magnesium or aluminum is more preferable.

Specific examples of higher fatty acid metal salts include calcium stearate, aluminum stearate, zinc stearate, magnesium stearate, calcium montanate, sodium montanate, and calcium palmitate.
Among them, as the higher fatty acid metal salt, a metal salt of montanic acid or a metal salt of stearic acid is preferable.

(higher fatty acid ester)
Higher fatty acid esters are esters of higher fatty acids and alcohols.
As the higher fatty acid ester, an ester of an aliphatic carboxylic acid having 8 to 40 carbon atoms and an aliphatic alcohol having 8 to 40 carbon atoms is preferable.
Examples of aliphatic alcohols having 8 to 40 carbon atoms include stearyl alcohol, behenyl alcohol, and lauryl alcohol.

Specific examples of higher fatty acid esters include stearyl stearate and behenyl behenate.

(higher fatty acid amide)
A higher fatty acid amide is an amide compound of a higher fatty acid.
Examples of higher fatty acid amides include stearic acid amide, oleic acid amide, erucic acid amide, ethylenebisstearylamide, ethylenebisoleylamide, N-stearyl stearic acid amide, N-stearyl erucic acid amide and the like.
These higher fatty acids, higher fatty acid metal salts, higher fatty acid esters and higher fatty acid amides may be used singly or in combination of two or more.

[(F) Thermal stabilizer]
(F) Heat stabilizers include, but are not limited to, phenol-based heat stabilizers, phosphorus-based heat stabilizers, amine-based heat stabilizers, Groups 3, 4 and 11 of the periodic table of the elements. Examples thereof include metal salts of elements of Groups 1 to 14, halides of alkali metals and alkaline earth metals, and the like.

(Phenolic heat stabilizer)
Phenolic heat stabilizers include, but are not limited to, hindered phenol compounds. Hindered phenol compounds have the property of imparting excellent heat resistance and light resistance to resins such as polyamides and fibers.

Examples of the hindered phenol compound include, but are not limited to, N,N'-hexane-1,6-diylbis[3-(3,5-di-t-butyl-4-hydroxyphenylprop onamide), pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-t-butyl- 4-hydroxy-hydrocinnamamide), triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 3,9-bis{2-[3-(3 -t-butyl-4-hydroxy-5-methylphenyl)propynyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5]undecane, 3,5-di-t -butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and 1,3, 5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid and the like.
These hindered phenol compounds may be used singly or in combination of two or more.
In particular, from the viewpoint of improving heat aging resistance, the hindered phenol compound includes N,N'-hexane-1,6-diylbis[3-(3,5-di-t-butyl-4-hydroxyphenylpropionamide )] is preferred.

When using a phenolic heat stabilizer, the content of the phenolic heat stabilizer in the polyamide composition is preferably 0.01% by mass or more and 1% by mass or less with respect to the total mass of the polyamide composition, and 0.1 % by mass or more and 1 mass % or less is more preferable.
When the content of the phenolic heat stabilizer is within the above range, the heat aging resistance of the polyamide composition can be further improved and the amount of gas generated can be further reduced.

(Phosphorus heat stabilizer)
Examples of phosphorus-based heat stabilizers include, but are not limited to, pentaerythritol-type phosphite compounds, trioctylphosphite, trilaurylphosphite, tridecylphosphite, octyldiphenylphosphite, trisisodecyl Phosphite, phenyldiisodecylphosphite, phenyldi(tridecyl)phosphite, diphenylisooctylphosphite, diphenylisodecylphosphite, diphenyl(tridecyl)phosphite, triphenylphosphite, tris(nonylphenyl)phosphite, tris(2 ,4-di-t-butylphenyl)phosphite, tris(2,4-di-t-butyl-5-methylphenyl)phosphite, tris(butoxyethyl)phosphite, 4,4'-butylidene-bis( 3-methyl-6-t-butylphenyl-tetra-tridecyl)diphosphite, tetra(C12-C15 mixed alkyl)-4,4'-isopropylidene diphenyl diphosphite, 4,4'-isopropylidenebis(2-t -butylphenyl)-di(nonylphenyl)phosphite, tris(biphenyl)phosphite, tetra(tridecyl)-1,1,3-tris(2-methyl-5-t-butyl-4-hydroxyphenyl)butanedi Phosphites, tetra(tridecyl)-4,4'-butylidenebis(3-methyl-6-t-butylphenyl) diphosphite, tetra(C1-C15 mixed alkyl)-4,4'-isopropylidene diphenyl diphosphite, tris (mono, dimixed nonylphenyl) phosphite, 4,4′-isopropylidenebis(2-t-butylphenyl)-di(nonylphenyl)phosphite, 9,10-di-hydro-9-oxa-9- Oxa-10-phosphaphenanthrene-10-oxide, tris(3,5-di-t-butyl-4-hydroxyphenyl)phosphite, hydrogenated-4,4′-isopropylidene diphenyl polyphosphite, bis (Octylphenyl)-bis(4,4′-butylidenebis(3-methyl-6-t-butylphenyl))-1,6-hexanol diphosphite, hexatridecyl-1,1,3-tris(2- methyl-4-hydroxy-5-t-butylphenyl)diphosphite, tris(4,4'-isopropylidenebis(2-t-butylphenyl))phosphite, tris(1,3-stearoyloxyisopropyl)phosphite, 2,2-methylenebis(4,6-di-t-butylphenyl)octylphosphite, 2,2-methylenebis(3-methyl-4,6-di-t-butylphenyl)2-ethylhexylphosphite, tetrakis ( 2,4-di-t-butyl-5-methylphenyl)-4,4'-biphenylene diphosphite and tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene diphosphite etc.
These phosphorus-based heat stabilizers may be used alone or in combination of two or more.
Among them, as the phosphorus-based heat stabilizer, pentaerythritol type phosphite compound and tris(2,4-di-t-butylphenyl ) one or more selected from the group consisting of phosphites.

Examples of pentaerythritol-type phosphite compounds include, but are not limited to, 2,6-di-t-butyl-4-methylphenyl-phenyl-pentaerythritol diphosphite, 2,6-di- t-butyl-4-methylphenyl-methyl-pentaerythritol diphosphite, 2,6-di-t-butyl-4-methylphenyl-2-ethylhexyl-pentaerythritol diphosphite, 2,6-di-t- Butyl-4-methylphenyl-isodecyl-pentaerythritol diphosphite, 2,6-di-t-butyl-4-methylphenyl-lauryl-pentaerythritol diphosphite, 2,6-di-t-butyl-4- Methylphenyl-isotridecyl-pentaerythritol diphosphite, 2,6-di-t-butyl-4-methylphenyl-stearyl pentaerythritol diphosphite, 2,6-di-t-butyl-4-methylphenyl cyclohexyl -pentaerythritol diphosphite, 2,6-di-t-butyl-4-methylphenyl-benzyl-pentaerythritol diphosphite, 2,6-di-t-butyl-4-methylphenyl ethyl cellosolve-pentaerythritol Diphosphite, 2,6-di-t-butyl-4-methylphenyl-butylcarbitol-pentaerythritol diphosphite, 2,6-di-t-butyl-4-methylphenyl-octylphenyl-pentaerythritol diphosphite phosphites, 2,6-di-t-butyl-4-methylphenyl-nonylphenyl pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, Bis(2,6-di-t-butyl-4-ethylphenyl) pentaerythritol diphosphite, 2,6-di-t-butyl-4-methylphenyl-2,6-di-t-butylphenyl-penta Erythritol diphosphite, 2,6-di-t-butyl-4-methylphenyl-2,4-di-t-butylphenyl-pentaerythritol diphosphite, 2,6-di-t-butyl-4-methyl Phenyl-2,4-di-t-octylphenyl-pentaerythritol diphosphite, 2,6-di-t-butyl-4-methylphenyl-2-cyclohexylphenyl-pentaerythritol diphosphite, 2,6-di -t-amyl-4-methylphenyl-phenyl pentaerythritol diphosphite, bis(2,6-di-t-amyl-4-methylphenyl)pentaerythritol diphosphite, and bis(2,6- and di-t-octyl-4-methylphenyl)pentaerythritol diphosphite.
These pentaerythritol-type phosphite compounds may be used alone or in combination of two or more.
Among them, as the pentaerythritol type phosphite compound, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2 ,6-di-t-butyl-4-ethylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-amyl-4-methylphenyl)pentaerythritol diphosphite, and bis(2,6 -di-t-octyl-4-methylphenyl)pentaerythritol diphosphite is preferably one or more selected from the group consisting of bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite Fight is more preferred.

When using a phosphorus-based heat stabilizer, the content of the phosphorus-based heat stabilizer in the polyamide composition is preferably 0.01% by mass or more and 1% by mass or less with respect to the total mass of the polyamide composition, and 0.1 % by mass or more and 1 mass % or less is more preferable.
When the content of the phosphorus-based heat stabilizer is within the above range, the heat aging resistance of the polyamide composition can be further improved, and the amount of gas generated can be further reduced.

(Amine heat stabilizer)
Examples of amine heat stabilizers include, but are not limited to, 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetra methylpiperidine, 4-acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(phenylacetoxy)-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6, 6-tetramethylpiperidine, 4-methoxy-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6, 6-tetramethylpiperidine, 4-benzyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4-(ethylcarbamoyloxy)-2,2 ,6,6-tetramethylpiperidine, 4-(cyclohexylcarbamoyloxy)-2,2,6,6-tetramethylpiperidine, 4-(phenylcarbamoyloxy)-2,2,6,6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidyl)-carbonate, bis(2,2,6,6-tetramethyl-4-piperidyl)-oxalate, bis(2,2,6,6-tetra methyl-4-piperidyl)-malonate, bis(2,2,6,6-tetramethyl-4-piperidyl)-sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl)-adipate, bis (2,2,6,6-tetramethyl-4-piperidyl)-terephthalate, 1,2-bis(2,2,6,6-tetramethyl-4-piperidyloxy)-ethane, α,α'-bis (2,2,6,6-tetramethyl-4-piperidyloxy)-p-xylene, bis (2,2,6,6-tetramethyl-4-piperidyl tolylene-2,4-dicarbamate, bis ( 2,2,6,6-tetramethyl-4-piperidyl)-hexamethylene-1,6-dicarbamate, tris(2,2,6,6-tetramethyl-4-piperidyl)-benzene-1,3, 5-tricarboxylate, tris(2,2,6,6-tetramethyl-4-piperidyl)-benzene-1,3,4-tricarboxylate, 1-[2-{3-(3,5-di -t-butyl-4-hydroxyphenyl)propionyloxy}butyl]-4-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]2,2,6,6-tetramethyl Piperidine, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and β,β,β',β'-tetramethyl-3,9-[2 ,4,8,10-tetraoxaspiro(5,5)undecane]condensates with diethanol.
These amine heat stabilizers may be used alone or in combination of two or more.

When using an amine-based heat stabilizer, the content of the amine-based heat stabilizer in the polyamide composition is preferably 0.01% by mass or more and 1% by mass or less with respect to the total mass of the polyamide composition, and 0.1 % by mass or more and 1 mass % or less is more preferable.
When the content of the amine-based heat stabilizer is within the above range, the heat aging resistance of the polyamide composition can be further improved, and the amount of gas generated can be further reduced.

(Metal salts of elements of Groups 3, 4 and 11 to 14 of the Periodic Table of Elements)
The metal salts of elements belonging to groups 3, 4 and 11 to 14 of the periodic table are not particularly limited as long as they are salts of metals belonging to these groups.
Among them, copper salts are preferable from the viewpoint of further improving the heat aging resistance of the polyamide composition. Such copper salts include, but are not limited to, copper halides, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, copper salicylate, copper nicotinate, stearic acid Copper complex salts in which copper is coordinated to copper or a chelating agent can be mentioned.
Examples of copper halides include copper iodide, cuprous bromide, cupric bromide, and cuprous chloride.
Chelating agents include, for example, ethylenediamine and ethylenediaminetetraacetic acid.
These copper salts may be used singly or in combination of two or more.
Among them, the copper salt is preferably one or more selected from the group consisting of copper iodide, cuprous bromide, cupric bromide, cuprous chloride and copper acetate, and consists of copper iodide and copper acetate. One or more selected from the group is more preferable. When the preferred copper salts listed above are used, the heat aging resistance is excellent, and the metal corrosion of the screw and cylinder during extrusion (hereinafter sometimes simply referred to as "metal corrosion") is more effectively suppressed. A polyamide composition is obtained.

(F) When using a copper salt as a heat stabilizer, the content of the copper salt in the polyamide composition is 0 with respect to the total mass of the polyamide ((A) aliphatic polyamide and (B) semi-aromatic polyamide) 0.01% by mass or more and 0.60% by mass or less is preferable, and 0.02% by mass or more and 0.40% by mass or less is more preferable.
When the content of the copper salt is within the above range, the heat aging resistance of the polyamide composition can be further improved, and copper precipitation and metal corrosion can be more effectively suppressed.

In addition, the content concentration of the copper element derived from the above copper salt is, from the viewpoint of improving the heat aging resistance of the polyamide composition, polyamide ((A) polyamide resin pellets and (B) crystalline polyamide) 10 ⁶ parts by mass ( 1,000,000 parts by mass), preferably 10 to 2,000 parts by mass, more preferably 30 to 1,500 parts by mass, and even more preferably 50 to 500 parts by mass.

(halides of alkali metals and alkaline earth metals)
Halides of alkali metals and alkaline earth metals include, but are not limited to, potassium iodide, potassium bromide, potassium chloride, sodium iodide, sodium chloride, and the like.
These alkali metal and alkaline earth metal halides may be used singly or in combination of two or more.
Among them, the halides of alkali metals and alkaline earth metals are preferably one or more selected from the group consisting of potassium iodide and potassium bromide from the viewpoint of improving heat aging resistance and suppressing metal corrosion. Potassium is more preferred.

When alkali metal and alkaline earth metal halides are used, the content of the alkali metal and alkaline earth metal halides in the polyamide composition is the polyamide ((A) polyamide resin pellets and (B) crystalline polyamide) 0.05 to 20 parts by mass is preferable, and 0.2 to 10 parts by mass is more preferable with respect to 100 parts by mass.
When the content of the alkali metal and alkaline earth metal halides is within the above range, the heat aging resistance of the polyamide composition is further improved, and copper precipitation and metal corrosion can be more effectively suppressed. can.

The component (F) of the heat stabilizer explained above may be used alone or in combination of two or more.
Among them, the heat stabilizer (F) is preferably a mixture of a copper salt and an alkali metal or alkaline earth metal halide from the viewpoint of further improving the heat aging resistance of the polyamide composition.

The content ratio of the copper salt and the alkali metal and alkaline earth metal halides is preferably 2/1 or more and 40/1 or less, and 5/1 or more and 30/1 in terms of the molar ratio of halogen to copper (halogen/copper). 1 or less is more preferable.
When the molar ratio of halogen to copper (halogen/copper) is within the above range, the heat aging resistance of the polyamide composition can be further improved.
Further, when the molar ratio of halogen to copper (halogen/copper) is equal to or higher than the above lower limit, precipitation of copper and metal corrosion can be more effectively suppressed. On the other hand, when the molar ratio of halogen to copper (halogen/copper) is equal to or less than the above upper limit, corrosion of the screw of the molding machine can be prevented more effectively without substantially impairing the mechanical properties (toughness, etc.).

[(G) Other polymers]
(G) Other polymers are not limited to the following as long as they are other than the above (A) polyamide resin pellets and the above (B) crystalline polyamides. Examples include polyesters, liquid crystal polyesters, and polyphenylenes. Sulfides, polycarbonates, polyarylates, phenolic resins, epoxy resins and the like can be mentioned.

(polyester)
Examples of polyester include, but are not limited to, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene terephthalate, and polyethylene naphthalate.

The content of (G) other polymer in the polyamide composition of the present embodiment is preferably 1 part by mass or more and 200 parts by mass or less, and 5 parts by mass or more and 100 parts by mass with respect to 100 parts by mass of the total resin in the polyamide composition. It is more preferably 5 parts by mass or less and 50 parts by mass or less. When the content of (G) other polymer in the polyamide composition of the present embodiment is within the above range, the polyamide composition can be made more excellent in heat resistance and releasability.

[(H) At least one selected from the group consisting of metal phosphite and metal hypophosphite]
(H) metal phosphite and metal hypophosphite, for example, elements, manganese, zinc, aluminum, ammonia, alkylamines, cycloalkylamines or salts with diamines.
Among them, sodium hypophosphite, calcium hypophosphite, or magnesium hypophosphite is preferable as the metal phosphite and the metal hypophosphite.
By including at least one selected from the group consisting of these metal phosphites and metal hypophosphites, it is possible to obtain a polyamide composition that is more excellent in extrusion processability and molding process stability.

[(I) Phosphite Ester Compound]
(I) Examples of the phosphite compound include triphenyl phosphite and tributyl phosphite.
By adding a phosphite ester compound, it is possible to obtain a polyamide composition that is more excellent in extrusion processability and molding process stability.

Specific examples of the phosphite compound include trioctylphosphite, trilaurylphosphite, tridecylphosphite, octyl-diphenylphosphite, trisisodecylphosphite, phenyldiisodecylphosphite, phenyldi(tridecyl)phosphite, Phyto, diphenylisooctylphosphite, diphenylisodecylphosphite, diphenyltridecylphosphite, triphenylphosphite, tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, bis [2,4-bis(1,1-dimethylethyl)-6-methylphenyl]ethylphosphite, bis(2,4-di-t-butylphenyl)pentaerythritol-di-phosphite, bis(2,6 -di-t-butyl-4-methylphenyl)pentaerythritol-di-phosphite, 2,2-methylenebis(4,6-di-t-butylphenyl)octylphosphite, 4,4'-butylidene-bis( 3-methyl-6-t-butylphenyl-di-tridecyl)phosphite, 1,1,3-tris(2-methyl-4-ditridecylphosphite-5-t-butyl-phenyl)butane, 4,4 '-isopropylidenebis(phenyl-dialkylphosphite), tris(2,4-di-t-butylphenyl)phosphite, 2,2-methylenebis(4,6-di-t-butylphenyl)octylphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol-di-phosphite and the like.
These phosphite ester compounds may be used singly or in combination of two or more.

[(J) Other additives]
The polyamide composition obtained by the production method of the present embodiment contains, in addition to the above components (A) and (B), within a range that does not impair the effects of the polyamide composition obtained by the production method of the present embodiment. It may contain (J) other additives commonly used in polyamide compositions. (J) Other additives include, for example, colorants such as pigments and dyes (including colored masterbatches), flame retardants, fibrillating agents, fluorescent bleaching agents, plasticizers, antioxidants, ultraviolet absorbers, and electrifying agents. Inhibitors, fluidity improvers, spreading agents, elastomers and the like can be mentioned.
When the polyamide composition obtained by the production method of the present embodiment contains (J) other additives, the content of (J) other additives varies depending on the type and application of the polyamide composition. , is not particularly limited as long as it does not impair the effects of the polyamide composition obtained by the production method of the present embodiment.

<Physical properties of polyamide composition>
[Weight Average Molecular Weight of Polyamide Composition]
The weight average molecular weight Mw can be used as an index of the molecular weight of the polyamide composition. It is preferable that the weight average molecular weight Mw of the polyamide composition has additivity, and the weight average molecular weight Mw of the polyamide resin pellet (A) × the ratio of A in the polyamide resin (A / (A + B)) + the weight of the crystalline polyamide More preferably, the average molecular weight Mw (B)×the ratio of B in the polyamide resin (B/(A+B))≈Mw. Specifically, Mw(A)×(A/(A+B))+Mw(B)×(B/(A+B)) is preferably Mw±1500, more preferably Mw±1000, and even more preferably Mw±500. When the weight-average molecular weight Mw is within the above range, it is possible to obtain a polyamide that is less affected by a decrease in molecular weight due to moisture content and has excellent mechanical properties, particularly water absorption stiffness, hot stiffness, fluidity, and the like. In addition, the polyamide composition containing the component represented by (C) the inorganic filler has excellent surface appearance.
As a method for controlling the weight average molecular weight Mw of the polyamide composition within the above range, the weight average molecular weights Mw (A) and Mw (B) of (A) the polyamide resin pellets and (B) the crystalline polyamide are adjusted to the ranges described above. and the use of (A) polyamide resin pellets having a moisture content that does not lower the weight average molecular weight Mw.
The weight-average molecular weight Mw can be measured using GPC as described later in Examples.

<Application>
The polyamide composition obtained by the production method of the present embodiment has excellent mechanical properties, particularly water absorption rigidity, heat rigidity, fluidity, surface appearance, etc. It can be suitably used as a molding material for various parts such as for daily use and household items.

EXAMPLES The present invention will be described in detail below with reference to specific examples and comparative examples, but the present invention is not limited to the following examples. In addition, Examples 3 and 6 are reference examples.

<Raw material of polyamide composition>
First, (A) polyamide resin pellets, (B) crystalline polyamide and (C) inorganic filler used in Examples and Comparative Examples are shown below.

[(A) Polyamide resin pellets]
A-1: Polyamide 6I Mw = 20000, enthalpy of crystallization of 0 J/g, water content of 5000 ppm
A-2: Polyamide 6I Mw = 20000, enthalpy of crystallization is 0 J/g, water content is 3200 ppm
A-3: Polyamide 6I Mw = 20000, enthalpy of crystallization is 0 J/g, water content is 2600 ppm
A-4: Polyamide 6I Mw = 20000, enthalpy of crystallization is 0 J/g, water content is 1000 ppm
A-5: Polyamide 6I Mw = 20000, enthalpy of crystallization is 0 J/g, water content is 9500 ppm

[(B) Crystalline Polyamide]
B-1: Polyamide 66 Mw = 35000

(C) Inorganic filler C-1: glass fiber (GF) manufactured by Nippon Electric Glass, trade name “ECS03T275H”, number average fiber diameter (average particle diameter) 10 μm (perfect circle), cut length 3 mm
In addition, in the present Example, the average fiber diameter of the glass fiber was measured as follows.
First, pellets of the polyamide composition were placed in an electric furnace to incinerate organic matter contained in the pellets of the polyamide composition. 100 or more arbitrarily selected glass fibers from the residue after the treatment are observed with a scanning electron microscope (SEM), and the fiber diameters of these glass fibers are measured to obtain the number average fiber diameter. rice field.

<Production of (A) polyamide resin pellets and (B) crystalline polyamide>
[(A) polyamide resin pellets and (B) raw materials for crystalline polyamide]
(A) Polyamide resin pellets and (B) crystalline polyamide used in Examples and Comparative Examples were produced using the following (a) dicarboxylic acid and (b) diamine as appropriate.

((a) dicarboxylic acid)
(a-1) adipic acid (ADA) (manufactured by Wako Pure Chemical Industries)
(a-2) isophthalic acid (IPA) (manufactured by Wako Pure Chemical Industries)

((b) diamine)
(b-1) 1,6-diaminohexane (hexamethylenediamine) (C6DA) (manufactured by Tokyo Chemical Industry Co., Ltd.)

Next, a method for producing (A) polyamide resin pellets (A-1 to A-5) and (B) crystalline polyamide (B-1) using the raw materials described above will be described.

[Example 1] Production of Polyamide Resin Pellets (A-1) (Polyamide 6I) Polymerization reaction of polyamide was carried out as follows by the “hot melt polymerization method”.
First, 1500 g of an equimolar salt of isophthalic acid and hexamethylenediamine, 0.3 mol% excess adipic acid with respect to all equimolar salt components, and 1.0 mol% excess with respect to all equimolar salt components Acetic acid was dissolved in 1500 g of distilled water to prepare an equimolar 50% by mass uniform aqueous solution of the raw material monomer. Then, 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 was 265°C.
After that, pressurize with nitrogen, extrude the polymerization reaction product as a strand from the lower spinneret (nozzle), perform water cooling for 5 seconds, cutting, and dehydration for 30 seconds to obtain (A-1) polyamide resin pellets (polyamide 6I). discharged. The obtained pellets had a weight average molecular weight Mw (A) of 20,000, a crystallization enthalpy of 0 J/g, and a water content of 5,000 ppm. Physical properties are shown in Table 1 below.

[Example 2] Production of polyamide resin pellets (A-2) (polyamide 6I) Pellets obtained using the same method as the above "polyamide resin pellets (A-1) (polyamide 6I)" were heated at 80 ° C. By drying in a nitrogen atmosphere for 2 hours, polyamide resin pellets (A-2) (polyamide 6I) were obtained. The obtained pellets had a weight average molecular weight Mw (A) of 20,000, a crystallization enthalpy of 0 J/g, and a water content of 3,200 ppm. Physical properties are shown in Table 1 below.

[Example 3] Production of polyamide resin pellets (A-3) (polyamide 6I) Pellets obtained using the same method as the above "polyamide resin pellets (A-1) (polyamide 6I)" were heated at 80 ° C. By drying in a nitrogen atmosphere for 3 hours, polyamide resin pellets (A-3) (polyamide 6I) were obtained. The obtained pellets had a weight average molecular weight Mw (A) of 20,000, a crystallization enthalpy of 0 J/g, and a water content of 2,600 ppm. Physical properties are shown in Table 1 below.

[Comparative Example 1] Production of polyamide resin pellets (A-4) (polyamide 6I) Pellets obtained using the same method as the above "polyamide resin pellets (A-1) (polyamide 6I)" were heated at 80 ° C. By drying in a nitrogen atmosphere for 7 hours, polyamide resin pellets (A-4) (polyamide 6I) were obtained. The obtained pellets had a weight average molecular weight Mw (A) of 20,000, a crystallization enthalpy of 0 J/g, and a water content of 1,000 ppm. Physical properties are shown in Table 1 below.

[Comparative Example 2] Production of polyamide resin pellets (A-5) (polyamide 6I) Pellets obtained using the same method as the above "polyamide resin pellets (A-1) (polyamide 6I)" are immersed in water. By doing so, polyamide resin pellets (A-5) (polyamide 6I) were obtained. The obtained pellets had a weight average molecular weight Mw (A) of 20,000, a crystallization enthalpy of 0 J/g, and a water content of 9,500 ppm. Physical properties are shown in Table 1 below.

[Production Example 1] Production of Crystalline Polyamide (B-1) (Polyamide 66) Polymerization reaction of polyamide was carried out as follows by the “hot melt polymerization method”.
First, 1,500 g of an equimolar salt of adipic acid and hexamethylenediamine was dissolved in 1,500 g of distilled water to prepare an equimolar 50 mass % uniform aqueous solution of the raw material monomer. This aqueous solution was charged into an autoclave having an internal volume of 5.4 L, and was purged with nitrogen. Then, 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 was 265°C. After that, pressurize with nitrogen, extrude the polymerized reaction product as a strand from the lower spinneret (nozzle), perform water cooling for 5 seconds, cutting, and dehydration for 30 seconds. After drying for 12 hours under low temperature, pellets of crystalline polyamide (B-1) (polyamide 66) were obtained. The obtained pellets had a weight average molecular weight Mw (B) of 35,000.

<Methods for measuring physical properties of (A) polyamide resin pellets and (B) crystalline polyamide>
[Physical property 1] Weight average molecular weight Mw
The weight average molecular weight Mw was measured using gel permeation chromatography (GPC). Specific measurement conditions are as shown below. Also, the weight average molecular weight Mw was calculated in terms of a polymethyl methacrylate (PMMA) standard sample.

(Measurement condition)
Measuring device: HLC-8020 manufactured by Tosoh Corporation
Solvent: Hexafluoroisopropanol Standard sample: PMMA (manufactured by Polymer Laboratories)

[Physical Property 2] Moisture Content Moisture content was measured according to ISO15512 using a Karl Fischer moisture meter (manufactured by Mitsubishi Chemical Analytech Co., Ltd., coulometric titration type trace moisture measuring device CA-200).

<Evaluation of Polyamide Composition>
[Evaluation 1] Evaluation of coloration by b value For the polyamide composition pellets obtained in Examples and Comparative Examples, the b value was measured by a reflection method using a color difference meter ZE-2000 manufactured by Nippon Denshoku Co., Ltd. Specifically, a pellet sample of the polyamide composition was laid out to a thickness of 13 mm using a dedicated jig, and the measurement was performed by projecting light from an opening of 10 mmφ. Based on the obtained b value, the coloration of each pellet was evaluated according to the following evaluation criteria.
(Evaluation criteria)
b value less than 17.50: Almost no coloration, more preferred.
b value of 17.50 or more and less than 18.00: Slightly colored, but preferable.
b value is 18.00 or more and less than 18.50: There is coloring, but it is practically usable.
b value of 18.50 or more: Colored and unusable.

[Evaluation 2] Evaluation of Strand At the time of producing pellets of the polyamide compositions of Examples and Comparative Examples, the state of strands was evaluated according to the following evaluation criteria.
(Evaluation criteria)
◯: The strand is pulled and can be cut.
x: A strand breaks.

<Production of Polyamide Composition>
[Examples 4-6 and Comparative Examples 3-4] Production of pellets of polyamide composition The (A) polyamide resin pellets, the (B) crystalline polyamide and the (C) inorganic filler described in Table 1 below were used. Pellets of each polyamide composition were produced as follows, using types and proportions.

A twin-screw extruder (ZSK-26MC, manufactured by Coperion GmbH (Germany)) was used as an apparatus for producing the polyamide composition.
The twin-screw extruder has an upstream feed port on the first barrel from the upstream side of the extruder, a downstream first feed port on the sixth barrel, and a downstream second feed port on the ninth barrel. had Also, in the twin-screw extruder, the aspect ratio (l/d) was 48 and the number of barrels was 12.
In the twin-screw extruder, the temperature from the upstream supply port to the die was set to the melting point Tm2+20° C. of the crystalline polyamide (B-1), and the screw rotation speed was set to 250 rpm and the discharge rate was set to 25 kg/h.

(A) Polyamide resin pellets and (B) crystalline polyamide are dry-blended so as to have the types and ratios shown in Table 1 below, and then supplied from the upstream supply port of the twin-screw extruder, and the twin-screw extruder From the first supply port on the downstream side of (C), glass fiber (GF) is supplied as an inorganic filler, and the melt-kneaded product extruded from the die head is extruded as a strand, cooled and cut to obtain pellets of each polyamide composition. (containing glass fiber). The obtained pellets were evaluated using the above method, and the results are shown in Table 1 below.

As shown in Table 1, in the polyamide composition pellets (Examples 1 to 3) containing (A) polyamide resin pellets and (B) crystalline polyamide having a water content of 2600 ppm or more and 5000 ppm or less, coloring is suppressed, Moreover, strand breakage did not occur.
In addition, as the water content in the (A) polyamide resin pellets increased, the b value tended to decrease, suggesting that coloration was more effectively suppressed.

According to the polyamide resin pellets and the method for producing the same of the present embodiment, it is possible to suppress coloration of pellets and strand breakage during pellet production of a polyamide composition containing an amorphous semi-aromatic polyamide and a crystalline polyamide. The pellets of the resulting polyamide composition are excellent in mechanical properties, particularly water absorption rigidity, heat rigidity, fluidity, surface appearance, etc., and are used for automobiles, electrical and electronic applications, industrial materials, industrial materials, and It can be suitably used as a molding material for various parts for daily use and household items.

Claims (5)

Polyamide resin pellets containing polyamide 6I ,
Containing 90% by mass or more of the polyamide 6I with respect to the total mass of the polyamide resin pellets,
Polyamide resin pellets having a moisture content of 3200 ppm or more and 7500 ppm or less relative to the total mass of the polyamide resin pellets. A method for producing a polyamide resin pellet according to claim 1 ,
a polymerization step of polymerizing a dicarboxylic acid and a diamine to obtain the polyamide 6I ;
A pellet forming step of extruding the melt of polyamide 6I as a strand, cooling and cutting the extruded strand to obtain pellets of polyamide 6I ;
An adjustment step of adjusting the moisture content of the pellets to 3200 ppm or more and 7500 ppm or less;
A manufacturing method, including: 3. The manufacturing method according to claim 2 , wherein the adjustment step is a drying step or a dehydration step. A polyamide composition comprising the polyamide resin pellets according to claim 1 as an amorphous semi-aromatic polyamide, polyamide 66 or polyamide 6 as a crystalline polyamide, and glass fiber as an inorganic filler. A melt-kneading step of melt-kneading raw material components including the polyamide resin pellets according to claim 1 , polyamide 66 or polyamide 6 as a crystalline polyamide , and glass fiber as an inorganic filler ,
A pellet forming step of obtaining pellets of the polyamide composition by extruding the melt-kneaded product obtained in the melt-kneading step as a strand, and cooling and cutting the extruded strand. A method for producing a polyamide composition.