JP2013095780A - Polyamide resin composition for injection molding and injection-molded product obtained by injection-molding the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin composition for injection molding including a polyamide resin whereby, in comparison with a conventional aliphatic polyamide resin, sufficient relative viscosity ηr, a wider moldable temperature range, heat resistance and melt-moldability, and reduction in the number of molding cycles can be achieved and a molded product excellent in chemical resistance, hydrolysis resistance, and fuel barrier properties can be injection-molded without deteriorating low water absorbability; and to provide an injection-molded product which is obtained by injection-molding the polyamide resin composition, and is excellent in dimension stability with less warp.SOLUTION: The polyamide resin composition for injection molding includes the polyamide resin (component A). The component A is produced by binding a unit derived from a dicarboxylic acid to a unit derived from a diamine, wherein the dicarboxylic acid includes an oxalic acid (compound a), the diamine includes a 1,6-hexanediamine (compound b) and a 2-methyl-1,5-pentanediamine (compound c), and the molar ratio of the compound b to the compound c is 99:1 to 50:50.

Description

  The present invention relates to a polyamide resin composition for injection molding and an injection molded body obtained by injection molding the same.

Hereinafter, the name of the polyamide resin may be based on JIS K 6920-1.
Crystalline polyamides such as nylon 6 (PA6) and nylon 66 (PA66) are widely used as textiles for clothing, industrial materials, or general-purpose engineering plastics because of their excellent properties and ease of melt molding. However, on the other hand, problems such as changes in physical properties due to water absorption, acid, high-temperature alcohol, deterioration in hot water, etc. have been pointed out, and there is an increasing demand for polyamides with better dimensional stability and chemical resistance. ing.

  A polyamide resin using oxalic acid as a dicarboxylic acid component is called a polyoxamide resin, and is known to have a higher melting point and lower water absorption than other polyamide resins having the same amino group concentration (Patent Document 1). It is expected to be used in fields where the use of conventional polyamides, where changes in physical properties have become a problem, is difficult.

So far, polyoxamide resins using various aliphatic linear diamines as diamine components have been proposed. For example,
Non-Patent Document 1 discloses a polyoxamide resin using 1,6-hexanediamine as a diamine component,
Non-Patent Document 2 discloses a polyoxamide resin (hereinafter also referred to as PA92) in which the diamine component is 1,9-nonanediamine,
Patent Document 2 discloses a polyoxamide resin using various diamine components and dibutyl oxalate as a dicarboxylic acid ester,
Patent Document 3 discloses a polyoxamide resin using two kinds of diamines of 1,9-nonanediamine and 2-methyl-1,8-octanediamine as a diamine component in a specific ratio.

JP 2006-57033 A Japanese National Patent Publication No. 5-506466 WO2008 / 072754

S. W. Shalaby, J. et al. Polym. Sci. , 11, 1 (1973) L. Franco, et al. , Macromolecules, 31, 3912 (1998).

However,
Regarding the polyoxamide resin disclosed in Non-Patent Document 1, the melting point (about 320 ° C.) is close to the thermal decomposition temperature (1% weight loss temperature in nitrogen; about 310 ° C.), so that melt polymerization and melt molding are difficult. It is not something that can withstand practical use,
The polyoxamide resin disclosed in Non-Patent Document 2 discloses a production method and crystal structure when diethyl oxalate is used as the oxalic acid source, and PA92 obtained here has an intrinsic viscosity of 0.97 dL / g. , A polymer having a melting point of 246 ° C., and only a low molecular weight body that cannot be formed into a tough molded body has been obtained,
Regarding the polyoxamide resin disclosed in Patent Document 2, it is shown that PA92 having an intrinsic viscosity of 0.99 dL / g and a melting point of 248 ° C. is produced, but the low molecular weight is such that a tough molded body cannot be molded. There is a problem that only the body is obtained,
Regarding the polyoxamide resin disclosed in Patent Document 3, a polyoxamide resin using two kinds of diamines of 1,9-nonanediamine and 2-methyl-1,8-octanediamine as a diamine component in a specific ratio is shown. However, these polyoxamide resins have a wide moldable temperature range, excellent moldability, and low water absorption, chemical resistance, hydrolysis resistance, fuel barrier properties, etc., but the melting point is around 240 ° C., Heat resistance is slightly inferior for electrical and electronic equipment applications that require molding cycle properties and a high melting point.
Furthermore, when these conventional polyamide resins are injection-molded, molded articles that are required to have low warpage and excellent dimensional stability, for example, parts having complicated shapes, such as oil tanks and intake systems for two- and four-wheeled vehicles In some cases, manufacturing of parts, integrated parts thereof, electrical component cases, containers and the like cannot be sufficiently performed.

The problem to be solved by the present invention is:
Compared with conventional polyoxamide resin,
Melting point Tm (° C.) measured by differential scanning calorimetry measured at a rate of temperature increase of 10 ° C./min under a nitrogen atmosphere and measurement at a rate of temperature increase of 10 ° C./min under a nitrogen atmosphere Moldable temperature estimated from temperature difference (Td-Tm) (° C.) (hereinafter also referred to as temperature difference (Td-Tm)) from 1% weight loss temperature Td (° C.) (thermal decomposition temperature) in thermogravimetric analysis Wide,
Excellent heat resistance estimated from melting point Tm,
It has an appropriate melt viscosity and excellent melt moldability, and the molding cycle can be reduced.
Polyamide that can injection-mold molded products with superior chemical resistance, hydrolysis resistance, and fuel barrier properties compared to conventional aliphatic polyamide resins without impairing the low water absorption found in aliphatic linear polyoxamide resins An object of the present invention is to provide a polyamide resin composition for injection molding containing a resin, and an injection molded article having little warpage and excellent dimensional stability obtained by injection molding.

The present invention
(1) A polyamide resin composition for injection molding containing a polyamide resin (component A),
The component A is composed of a unit derived from a dicarboxylic acid and a unit derived from a diamine,
The dicarboxylic acid comprises oxalic acid (compound a);
The diamine comprises 1,6-hexanediamine (compound b) and 2-methyl-1,5-pentanediamine (compound c);
Injection molding a polyamide resin composition for injection molding in which the molar ratio of the compound b to the compound c is 99: 1 to 50:50, and (2) the polyamide resin composition for injection molding described in (1) above. It is the obtained injection-molded body.

According to the present invention,
Compared with conventional polyoxamide resin,
The moldable temperature range estimated from the temperature difference (Td−Tm) is wide.
Excellent heat resistance estimated from the melting point Tm,
It has an appropriate melt viscosity and excellent melt moldability, and the molding cycle can be reduced.
Polyamide that can injection-mold molded products with superior chemical resistance, hydrolysis resistance, and fuel barrier properties compared to conventional aliphatic polyamide resins without impairing the low water absorption found in aliphatic linear polyoxamide resins It is possible to provide a polyamide resin composition for injection molding containing a resin, and an injection molded article with little warpage and excellent dimensional stability obtained by injection molding.

Injection molded articles molded using the pellets obtained in Examples 1 to 7 and Comparative Examples 2 and 4.

[Component A]
(1) Configuration of Component A Component A, which is a polyamide resin in the present invention,
The dicarboxylic acid component is succinic acid and the diamine component consists of 1,6-hexanediamine and 2-methyl-1,5-pentanediamine,
A polyamide resin formed by bonding a unit derived from a dicarboxylic acid and a unit derived from a diamine,
The dicarboxylic acid comprises oxalic acid (compound a);
The diamine comprises 1,6-hexanediamine (compound b) and 2-methyl-1,5-pentanediamine (compound c);
The molar ratio of the compound b to the compound c is 99: 1 to 50:50,
Preferably, the relative viscosity ηr measured at 25 ° C. using a solution of Component A having a concentration of 1.0 g / dl in 96% sulfuric acid is 1.8 to 6.0.

  Component A uses compounds a, b and c, preferably polycondensation using a mixture thereof, so that it has a high molecular weight, a high melting point, a large difference between the melting point and the thermal decomposition temperature, and excellent melt moldability. Furthermore, it is excellent in chemical resistance, hydrolysis resistance and fuel barrier properties as compared with conventional polyamides without impairing the low water absorption seen in linear polyoxamide resins.

From the viewpoint of ensuring chemical resistance, hydrolysis resistance and fuel barrier properties, component A has a molar ratio of compound b to compound c:
Preferably, 99: 1 to 55:45 mol%,
More preferably, it is 99: 1-60: 40 mol%.
Hereinafter, the molar ratio of the compound b and the compound c also means the molar ratio of the unit derived from the compound b and the unit derived from the compound c in the component A.

When compound a (oxalic acid) is directly used as a raw material in the production of component A, compound a (succinic acid) itself is thermally decomposed, and the melting point of component A exceeds the thermal decomposition temperature. (Hereinafter, also referred to as oxalic acid source) and obtained by polycondensation of oxalic acid derived from the oxalic acid source and diamine. This oxalic acid is derived from an oxalic acid source such as oxalic acid diester, and any oxalic acid may be used as long as it has reactivity with an amino group.
As the oxalic acid source, oxalic acid diester is preferable from the viewpoint of suppressing side reactions in the polycondensation reaction. Dimethyl oxalate, diethyl oxalate, di-n- (or i-) propyl oxalate, di-n- (or i-, or t-) oxalate Examples thereof include oxalic acid diesters of aliphatic monohydric alcohols such as butyl, oxalic acid diesters of alicyclic alcohols such as dicyclohexyl oxalate, and oxalic acid diesters of aromatic alcohols such as diphenyl oxalate.
Among the oxalic acid diesters, oxalic acid diesters of aliphatic monohydric alcohols having more than 3 carbon atoms, oxalic acid diesters of alicyclic alcohols, and oxalic acid diesters of aromatic alcohols are more preferable,
Among them, dibutyl oxalate and diphenyl oxalate are more preferable,
More preferred is dibutyl oxalate.

(2) Relative viscosity of component A
Using oxalic acid as compound a as the carboxylic acid component,
As the diamine component, 1,6-hexanediamine as compound b and 2-methyl-1,5-pentanediamine as compound c are polycondensed so that the melting point is preferably in the range of 200 to 330 ° C. Compared to a polyamide resin obtained by polycondensation of compound a and compound b with a melting point exceeding 330 ° C. (hereinafter also referred to as comparative component A2), in the melt polymerization in the post-polymerization step of component A described later, Since it is not necessary to use an excessively high temperature condition in which a side reaction occurs and inhibits high molecular weight, high molecular weight (increasing relative viscosity) is possible.
Therefore, Component A has an excellent melt moldability because it can increase the relative viscosity as compared with the conventional polyamide resin.
In view of avoiding the tendency of the molded product after melt molding to become brittle and lowering the physical properties, to avoid the tendency to increase the melt viscosity at the time of melt molding and deteriorate the molding processability, the relative viscosity ηr and the melt viscosity are more than a certain level. From the viewpoint of being suitable for uses such as automobile parts and electrical / electronic parts that are preferably high and not excessively high, a 96% concentrated sulfuric acid solution having a concentration of component A of 1.0 g / dl is used. The relative viscosity ηr measured at 25 ° C. is preferably 1.8 to 6.0, more preferably 1.8 to 4.5, more preferably 1.8 to 3.0, still more preferably. May be 1.85 to 2.5, more preferably 1.85 to 2.2.
In the melt polymerization in the post-polymerization step of component A described later, the relative viscosity ηr can be increased by increasing the degree of vacuum.

  From the same viewpoint, the melt viscosity of component A is preferably 100 to 700 Pa · s, more preferably 110 to 600 Pa · s, still more preferably 120 to 500 Pa · s, still more preferably 130 to 400 Pa · s, and further Preferably it is 150-300 Pa.s, More preferably, it is 160-220 Pa.s, More preferably, it is 170-200 Pa.s.

  Furthermore, from the same viewpoint, the number average molecular weight of Component A is preferably 10,000 to 50,000, more preferably 11,000 to 40,000, and still more preferably 11,000 to 35,000.

The number average molecular weight (Mn) is based on the signal intensity obtained from the 1H-NMR spectrum, for example, dibutyl oxalate as the oxalic acid source, 1,6-hexanediamine (compound b) and 2-methyl-1, as the diamine component. In the case of a polyamide produced using 5-pentanediamine (compound c) at a molar ratio of 90:10 [hereinafter abbreviated as PX6-2 (compound b / compound c = 90/10)], it is calculated by the following formula. did.
Mn = np × 170.21 + n (NH ₂ ) × 115.20 + n (OBu) × 129.13 + n (NHCHO) × 29.14
In addition, the measurement conditions of 1H-NMR are as follows.
・ Model used: Bruker Biospin AVANCE500
-Solvent: Bisulfuric acid-Integration frequency: 1024 times Each term in the above formula is defined as follows.
Np = Np / [(N (NH ₂ ) + N (NHCHO) + N (OBu)) / 2]
・ N (NH ₂ )
= N (NH ₂ ) / [(N (NH ₂ ) + N (NHCHO) + N (OBu)) / 2]
・ N (NHCHO)
= N (NHCHO) / [(N (NH ₂ ) + N (NHCHO) + N (OBu)) / 2]
・ N (OBu)
= N (OBu) / [(N (NH ₂ ) + N (NHCHO) + N (OBu)) / 2]
Np = Sp / sp-N (NHCHO)
N (NH ₂ ) = S (NH ₂ ) / s (NH ₂ )
N (NHCHO) = S (NHCHO) / s (NHCHO)
N (OBu) = S (OBu) / s (OBu)
However, each term has the following meaning.
Np: Total number of repeating units in the molecular chain excluding terminal units of PA62 (compound B / compound C = 90/10).
Np: the number of repeating units in the molecular chain per molecule.
Sp: PX6-2 (compound b / compound c = 90/10) excluding the signal based on the proton of the methylene group adjacent to the oxamide group in the repeating unit in the molecular chain (around 3.1 ppm) Integration value.
Sp: The number of hydrogens (4) counted in the integral value Sp.
· _N (NH 2): The total number of terminal amino groups of PX6-2 (Compound b / Compound c = 90/10).
N (NH ₂ ): number of terminal amino groups per molecule.
S (NH ₂ ): Integral value of a signal (around 2.6 ppm) based on the proton of the methylene group adjacent to the terminal amino group of PX6-2 (compound b / compound c = 90/10).
S (NH ₂ ): The number of hydrogens (2) counted in the integrated value S (NH ₂ ).
N (NHCHO): total number of terminal formamide groups of PX6-2 (compound b / compound c = 90/10).
N (NHCHO): number of terminal formamide groups per molecule.
-S (NHCHO): The integral value of the signal (7.8 ppm) based on the proton of the formamide group of PX6-2 (compound b / compound c = 90/10).
S (NHCHO): The number of hydrogens (one) counted in the integral value S (NHCHO).
N (OBu): the total number of terminal butoxy groups of PX6-2 (compound b / compound c = 90/10).
N (OBu): number of terminal butoxy groups per molecule.
S (OBu): integrated value of a signal (around 4.1 ppm) based on the proton of the methylene group adjacent to the oxygen atom of the terminal butoxy group of PX6-2 (compound b / compound c = 90/10).
S (OBu): The number of hydrogens (two) counted in the integral value S (OBu).

(3) Physical properties of component A Component A further changes the polycondensation ratio of compounds b and c,
The temperature difference (Td−Tm) is large compared to the comparative component A2, and small compared to the polyamide resin obtained by polycondensation of the compound a and the compound c (hereinafter also referred to as the comparative component A1).
The melting point Tm is low compared to the comparative component A2, high compared to the comparative component A1,
1% weight loss temperature Td is higher than the comparative component A1,
The saturated water absorption rate can be smaller than the comparative component A2 and larger than the comparative component A1.

That is, the component A is compared with the conventional polyoxamide resin,
Relative viscosity ηr (high molecular weight),
Moldable temperature range estimated from the temperature difference (Td−Tm),
Heat resistance estimated from melting point Tm,
Both melt moldability estimated from melt viscosity and low water absorption can be sufficiently secured.

  Component A has sufficient chemical resistance, resistance to resistance due to the high polymerization ratio (molar ratio) of compound b after sufficiently ensuring the moldable temperature range, heat resistance, melt moldability and low water absorption. Particularly contributes to hydrolyzability and fuel barrier properties.

From the viewpoint of sufficiently ensuring all of the moldable temperature range, heat resistance, melt moldability and low water absorption,
Tm is preferably 260 to 330 ° C, more preferably 265 to 330 ° C,
Td is preferably 341 to 370 ° C, more preferably 345 to 370 ° C, still more preferably 350 to 365 ° C,
The temperature difference (Td−Tm) is preferably 10 to 95 ° C., more preferably 20 to 95 ° C., still more preferably 25 to 95 ° C.,
The saturated water absorption is preferably 0 to 2.4, more preferably 1 to 2.4, still more preferably 2 to 2.4, and still more preferably 2.3 to 2.4.

(4) Production of Component A Component A can be produced using any method known as a method for producing polyamide, but from the viewpoint of high molecular weight and productivity,
Preferably, it is obtained by polycondensation reaction of diamine and oxalic acid diester batchwise or continuously.
More preferably, the diamine and the oxalic acid diester are obtained by a two-stage polymerization method comprising a pre-polycondensation step and a post-polycondensation step, or a pressure polymerization method described in WO2008-072754.
More preferable two-stage polymerization method and pressure polymerization method are specifically shown by the following operations.

(4-1) Two-stage polymerization method (i) Pre-polycondensation step: First, the inside of the reactor is purged with nitrogen, and then diamine (compounds b and c) and oxalic acid diester which is the oxalic acid source of compound a are mixed. When mixing, a solvent in which both the diamine and the oxalic acid diester are soluble may be used. As a solvent in which both the diamine component and the oxalic acid source component are soluble, toluene, xylene, trichlorobenzene, phenol, trifluoroethanol, and the like can be used, and toluene is particularly preferably used. For example, after heating the toluene solution which melt | dissolved diamine to 50 degreeC, oxalic acid diester is added with respect to this.
At this time, the charging ratio between the oxalic acid diester and the diamine is 0.8 to 1.5 (molar ratio), preferably 0.91 to 1.1 (molar ratio), from the viewpoint of increasing the molecular weight. Ratio), more preferably 0.99 to 1.01 (molar ratio).

  The temperature in the reactor charged in this way is increased under normal pressure while stirring and / or nitrogen bubbling. The reaction temperature is preferably controlled so that the final temperature reaches 80 to 150 ° C., preferably 100 to 140 ° C. The reaction time at the final temperature reached is 3-6 hours.

(Ii) Post-polycondensation step: In order to further increase the molecular weight, the polymer produced in the pre-polycondensation step is gradually heated in the reactor under normal pressure. From the final ultimate temperature of the pre-polycondensation step in the temperature rising process, that is, preferably from 80 to 150 ° C., finally,
The temperature is preferably 295 ° C. or higher and 350 ° C. or lower, more preferably 298 ° C. or higher and 345 ° C. or lower, more preferably 298 ° C. or higher and 340 ° C. or lower.
It is preferable to carry out the reaction while keeping the temperature rising time preferably 1 to 8 hours, more preferably 2 to 6 hours. Furthermore, in the post-polymerization step, polymerization can be performed under reduced pressure as necessary. A preferable final pressure in the case of carrying out the vacuum polymerization is 13.3 Pa to 0.1 MPa.

(4-2) Pressurized polymerization method First, diamine is placed in a pressure vessel and purged with nitrogen, and then heated to the reaction temperature under a sealing pressure. Thereafter, the oxalic acid compound is injected into the pressure vessel while maintaining the sealed pressure state at the reaction temperature, and the polycondensation reaction is started. The reaction temperature is not particularly limited as long as the polyamide produced by the reaction of the diamine and the oxalic acid compound can maintain a slurry or solution state and does not thermally decompose. For example, in the case of Component a, the reaction temperature is preferably 150 ° C to 250 ° C. Here, the charging ratio of dibutyl oxalate and diamine is 0.8 to 1.5 (molar ratio), preferably 0.91 to 1.1 (molar ratio), in terms of the molar amount of dibutyl oxalate / total molar amount of diamine. More preferably, it is 0.99 to 1.01 (molar ratio).
Next, while maintaining the inside of the pressure vessel in a sealed pressure state, the temperature is raised to a temperature not lower than the melting point of the polyamide resin and not pyrolyzed. For example, in the case of Component a, since the melting point is 245 to 300 ° C., the temperature is raised to 250 to 350 ° C., preferably 255 to 340 ° C., more preferably 260 to 335 ° C. The pressure in the pressure resistant container until reaching the predetermined temperature is adjusted to approximately 0.1 MPa, preferably 1 MPa to 0.2 MPa from the saturated vapor pressure of the alcohol to be generated. After reaching the predetermined temperature, the pressure is released while distilling off the produced alcohol, and the polycondensation reaction is continued under normal pressure nitrogen flow or reduced pressure as necessary. A preferable final pressure in the case of carrying out the vacuum polymerization is 13.3 Pa to 0.1 MPa.

(5) Component which can be used as dicarboxylic acid in component A In component A, other dicarboxylic acid components other than compound a can be used within a range not impairing the effects of the present invention.
As other dicarboxylic acid components other than compound a (oxalic acid),
Malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, 3,3-diethylsuccinic acid, azelaic acid, sebacic acid , Aliphatic dicarboxylic acids such as suberic acid,
In addition, alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid,
Further, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydi Aromatic dicarboxylic acids such as acetic acid, dibenzoic acid, 4,4′-oxydibenzoic acid, diphenylmethane-4,4′-dicarboxylic acid, diphenylsulfone-4,4′-dicarboxylic acid, 4,4′-biphenyldicarboxylic acid These may be added alone, or any mixture thereof may be added during the polycondensation reaction.
Furthermore, polyvalent carboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid can be used as long as melt molding is possible.
When other dicarboxylic acid components are used, the proportion thereof is 25 mol% or less, preferably 15 mol% or less, more preferably 10 mol% or less, and more preferably 5 mol% or less with respect to compound a (succinic acid). More preferably, it is more preferably 0 mol% (that is, the dicarboxylic acid component consists only of compound a). The molar ratio of the other dicarboxylic acid component to the compound a (succinic acid) also means the molar ratio of the unit derived from the compound a and the unit derived from the other dicarboxylic acid component in the component A.

In component A, other diamine components other than compounds b and c can be used within the range not impairing the effects of the present invention.
As other diamine components other than 1,6-hexanediamine and 2-methyl-1,5-pentanediamine, ethylenediamine, propylenediamine, 1,4-butanediamine, 1,9-nonanediamine, 2-methyl-1, 8-octanediamine, 1,8-octanediamine, 1,10-decanediamine, 1,11-undecanediamine,
1,12-dodecanediamine, 3-methyl-1,5-pentanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 5- Aliphatic diamines such as methyl-1,9-nonanediamine,
Furthermore, alicyclic diamines such as cyclohexanediamine, methylcyclohexanediamine, and isophoronediamine,
Furthermore, aromatic diamines such as p-phenylenediamine, m-phenylenediamine, p-xylenediamine, m-xylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylether ,
These may be added alone, or any mixture thereof may be added during the polycondensation reaction.
When other diamine components are used, the proportion thereof is 25 mol% or less, preferably 15 mol% or less, more preferably 10 mol% or less, still more preferably 5 mol% or less, with respect to compounds b and c. More preferably, it is 0 mol% (that is, the diamine component consists only of compounds b and c). In addition, the molar ratio of the other diamine component with respect to the compounds b and c also means the molar ratio of the units derived from the compounds b and c and the units derived from the other diamine components in the component A.

(6) Molding of component A As the molding method of component A, all known molding methods applicable to polyamide such as injection, extrusion, hollow, press, roll, foaming, vacuum / pressure air, and stretching can be used. From the viewpoint of shortening the molding cycle performance, it is particularly suitable for molding by injection molding, and can be processed into films, sheets, molded articles, fibers, etc. by these molding methods.

[Polyamide resin composition for injection molding]
(Content of component A)
The polyamide resin composition for injection molding of the present invention (hereinafter also referred to as a resin composition) has a good moldable temperature range, heat resistance, and melt moldability (hereinafter referred to as thermal characteristics) for improving productivity during injection molding. From the viewpoint of ensuring low water absorption, chemical resistance, hydrolysis resistance, fuel barrier properties and dimensional stability (particularly suppression of warpage) of injection molded products.
The content of Component A in the resin composition is preferably 50 to 100% by mass, more preferably 55 to 100% by mass, and still more preferably 60 to 100% by mass.

(Other ingredients)
For injection molding applications, it is preferable to include the following as other components.

(1) Polymer other than Component A In the resin composition of the present invention, if necessary, in order to utilize the characteristics of each polymer,
Other polyamides other than component A, such as at least one polyamide selected from the group consisting of polyoxamides, aromatic polyamides, aliphatic polyamides and alicyclic polyamides, and / or polymers other than polyamides, such as thermoplastic polymers An elastomer can be included.

  The polymer other than component A is not particularly limited as long as it does not impair the effects of the present invention, but is preferably 0 to 50 parts by mass, more preferably 0 to 40 parts by mass, and still more preferably, relative to 100 parts by mass of component A. Is 0-30 parts by mass.

(2) Additive The resin composition of the present invention can contain an additive as long as the effects of the present invention are not impaired. Examples of additives include pigments, dyes, colorants, heat resistance agents, antioxidants, weathering agents, UV absorbers, light stabilizers, lubricants, crystal nucleating agents, crystallization accelerators, mold release agents, and antistatic agents. , Stabilizers such as plasticizers and copper compounds, antistatic agents, flame retardants, glass fibers, lubricants, fillers, reinforcing fibers, reinforcing particles, foaming agents and the like.

The method for adding the polymer and / or additive other than the above component A is not particularly limited as long as each method can be dispersed in component A, and the component can be added at any time that does not impair the effect. A can be added.
For example, polymers and / or additives other than component A
It can also be added during or after the polycondensation reaction of component A.

(3) Layered silicate The resin composition of the present invention can produce an injection-molded body having only warp and excellent in dimensional stability with only component A, but in applications where high-precision dimensional stability is required. Can further contain a layered silicate in the resin composition of the present invention.
Further, by adding a layered silicate, it is possible to improve the rigidity, weather resistance and / or heat resistance, and barrier property against liquid or vapor of an injection-molded body produced from the resin composition of the present invention.

  The layered silicate is preferably a flat plate having a side length of 0.002 to 1 μm and a thickness of 6 to 20 mm. In addition, the layered silicate is preferably one in which each layer in the component A is uniformly dispersed with an interlayer distance of about 20 mm or more.

  Here, “interlayer distance” refers to the distance between the centroids of the plate-like layered silicate, and “uniformly dispersed” means that each layer exists mainly in a random state, and the layered silicate 50% by mass or more, preferably 70% by mass or more, is dispersed in a single layer without forming a multilayer.

  The amount of the layered silicate is not particularly limited as long as the effect of the layered silicate is exhibited, but the rigidity, weather resistance and / or heat resistance of the injection-molded product, and liquid or vapor From the viewpoint of improving the barrier properties against the above and from the viewpoint of securing the molding processability and impact resistance of the resin composition, it is preferably 0.05 to 10 parts by mass, more preferably 0. It is 05-8 mass parts, More preferably, it is 0.05-5 mass parts.

  As a raw material of the said layered silicate, the layered phyllosilicate mineral comprised from the layer of magnesium silicate or an aluminum silicate, ie, the aluminum silicate phyllosilicate, or the magnesium silicate phyllosilicate can be illustrated. Specific examples include smectite clay minerals such as montmorillonite, saponite, beidellite, nontronite, hectorite, and stevensite, vermiculite, halloysite, and the like. It may be what was done.

  In order to disperse the layered silicate in component A, a swelling agent is usually used. The swelling agent has a role of expanding the interlayer of the clay mineral and a role of giving the clay mineral a force for taking up the interlayer polymer. In the present invention, it is preferable to use 1,6-hexanediamine and 2-methyl-1,5-pentanediamine as the swelling agent.

  The layered silicate is preferably pulverized using a mixer, a ball mill, a vibration mill, a pin mill, a jet mill, a beating machine, or the like to have a desired shape and size in advance.

  The method for adding the layered silicate is not particularly limited as long as the layered silicate can be uniformly dispersed in the component A. For example, when the raw material of the layered silicate is a multilayered clay mineral, as disclosed in JP-A-62-74957, the layered silicate is ionized with hydrochloric acid or the like, and a swelling agent such as, for example, 1,6-hexanediamine and 2-methyl-1,5-pentanediamine are added to widen the space between the layers of the layered silicate in advance. Subsequently, the raw material of component A can be introduce | transduced between the said layers, and also the said raw material can be polymerized between the said layers.

  Alternatively, using an organic compound as a swelling agent, the layers may be preliminarily spread to about 100 mm or more and melt-mixed with component A to disperse each layer in a polyamide resin.

[Injection molded body]
The injection-molded article of the present invention (hereinafter also referred to as injection-molded article) is obtained by molding a resin composition in combination with, for example, extrusion molding, blow molding, compression molding, injection molding, etc., as well as injection molding. Can be produced.
The injection molded body is not particularly limited, but is a molded body that is required to have low warpage and excellent dimensional stability, for example, parts having complicated shapes, such as oil tanks for two- and four-wheeled vehicles, intake system parts, And molded articles suitable for the manufacture of integrated parts, electrical component cases, and other containers.
The injection-molded body also includes a welding joint member.

  More specifically, as an injection-molded body, for example, an intake system module component that integrates an intake system component such as an intake manifold of an automobile that requires high strength and durability, a cylinder head cover, an intake manifold, an air cleaner, and the like. Cooling system parts such as water inlets and water outlets, fuel system parts such as fuel injection and fuel delivery pipes, containers such as oil tanks, and electrical equipment cases such as switches.

[Examples and Comparative Examples]
In Examples 1-7, the polyamide resin composition for injection molding of the present invention was produced.
Examples 1 to 5 are polyamide resin compositions for injection molding composed of Component A, and Examples 6 and 7 are polyamide resin compositions for injection molding composed of Component A and glass fibers.

(1) Example 1 (component A: PX6-1)
In a pressure vessel with an internal volume of about 150 liters equipped with a stirrer, thermometer, torque meter, pressure gauge, raw material inlet directly connected with a diaphragm pump, nitrogen gas inlet, pressure outlet, pressure regulator and polymer outlet.
Mixture of compound a (1,6-hexanediamine) 15.407 kg (132.58 mol) and compound b (2-methyl-1,5-pentanediamine) 811.1 g (6.98 mol) (compound a and compound the molar ratio of b is 95: 5),
After pressurizing the interior of the pressure vessel to 0.5 MPa with nitrogen gas having a purity of 99.9999%,
Next, the operation of releasing nitrogen gas to normal pressure was repeated 5 times, and after nitrogen replacement,
The system was heated while stirring under a sealing pressure.
After bringing the temperature of dibutyl oxalate to 80 ° C. over about 30 minutes,
At the same time, 28.230 kg (139.56 mol) of dibutyl oxalate was supplied into the reaction vessel over about 17 minutes at a flow rate of 1.49 liters / minute by means of a diaphragm pump.
The internal pressure in the pressure vessel immediately after the supply increased to 0.35 MPa by butanol generated by the polycondensation reaction, and the temperature of the polycondensate increased to about 170 ° C.
Thereafter, the temperature was raised to 330 ° C. over 2 hours.
Meanwhile, the internal pressure was adjusted to 0.75 MPa while extracting the generated butanol from the pressure relief port. Immediately after the temperature of the polycondensate reached 330 ° C., butanol was extracted from the pressure relief port over about 20 minutes, and the internal pressure was brought to normal pressure.
From the normal pressure, the temperature was raised while flowing nitrogen gas at 1.5 liters / minute, and the reaction was carried out for 4.5 hours.
Thereafter, the stirring was stopped and the system was pressurized to 1 MPa with nitrogen and allowed to stand for about 10 minutes. Then, the pressure was released to an internal pressure of 0.1 MPa, and the polycondensate was extracted in a string form from the lower outlet of the pressure vessel.
The string-like polymer was immediately cooled with water, and the water-cooled string-like resin was pelletized with a pelletizer.
The obtained polyamide was a white tough polymer with ηr = 1.95.

(2) Example 2 (component A: PX6-2)
A mixture of 14.717 kg (126.64 mol) of compound a and 1.635 kg (14.07 mol) of compound b (molar ratio of compound a and compound b is 90:10) is charged.
Except for charging 28.462 kg (140.71 mol) of dibutyl oxalate,
Reaction was carried out in the same manner as in Example 1 to obtain polyamide.
The obtained polyamide was a white tough polymer with ηr = 2.05.

(3) Example 3 (component A: PX6-3)
A mixture of 12.16 kg (104.64 mol) of compound a and 5.212 kg (44.85 mol) of compound b (the molar ratio of compound a to compound b is 70:30) is charged.
At the same time, 30.238 kg (149.49 mol) of dibutyl oxalate was supplied into the reaction vessel by a diaphragm pump at a flow rate of 1.49 liters / minute over about 17 minutes.
The internal pressure in the pressure vessel immediately after the supply increased to 0.35 MPa by butanol generated by the polycondensation reaction, and the temperature of the polycondensate increased to about 170 ° C.
Thereafter, the temperature was raised to 290 ° C. over 1.5 hours.
Meanwhile, the internal pressure was adjusted to 0.5 MPa while extracting the generated butanol from the pressure relief port. Immediately after the temperature of the polycondensate reached 290 ° C., butanol was extracted from the pressure relief port over about 20 minutes, and the internal pressure was brought to normal pressure.
The temperature was raised from normal pressure while flowing nitrogen gas at 1.5 liters / minute, the temperature of the polycondensate was brought to 310 ° C. over about 1 hour, and the reaction was carried out at 310 ° C. for 1.5 hours. .
Thereafter, the stirring was stopped and the system was pressurized to 1 MPa with nitrogen and allowed to stand for about 10 minutes. Then, the pressure was released to an internal pressure of 0.1 MPa, and the polycondensate was extracted in a string form from the lower outlet of the pressure vessel.
The string-like polymer was immediately cooled with water, and the water-cooled string-like resin was pelletized with a pelletizer.
The obtained polyamide was a white tough polymer with ηr = 2.40.

(4) Example 4 (component A: PX6-4)
A mixture of 10.294 kg (88.583 mol) of compound a and 6.863 kg (59.057 mol) of compound b (molar ratio of compound a to compound b is 60:40) is charged.
29.864 kg (147.64 mol) of dibutyl oxalate was supplied into the reaction vessel at a flow rate of 1.49 liter / min by a diaphragm pump over about 17 minutes, and the temperature was raised.
The internal pressure in the pressure vessel immediately after the supply increased to 0.35 MPa by butanol generated by the polycondensation reaction, and the temperature of the polycondensate increased to about 170 ° C.
Thereafter, the temperature was raised to 275 ° C. over 1.5 hours.
Meanwhile, the internal pressure was adjusted to 0.5 MPa while extracting the generated butanol from the pressure relief port.
Immediately after the temperature of the polycondensate reached 270 ° C., butanol was extracted from the pressure release port over about 20 minutes, and the internal pressure was brought to normal pressure.
From the normal pressure, the temperature was raised while flowing nitrogen gas at 1.5 liters / minute, the temperature of the polycondensate was changed to 290 ° C. over about 1 hour, and the reaction was carried out at 290 ° C. for 2 hours.
Thereafter, the stirring was stopped and the system was pressurized to 1 MPa with nitrogen and allowed to stand for about 10 minutes. Then, the pressure was released to an internal pressure of 0.1 MPa, and the polycondensate was extracted in a string form from the lower outlet of the pressure vessel.
The string-like polymer was immediately cooled with water, and the water-cooled string-like resin was pelletized with a pelletizer.
The obtained polyamide was a white tough polymer, and ηr = 2.68.

(5) Example 5 (component A: PX6-5)
A mixture of 8.361 kg (71.947 mol) of compound a and 8.361 kg (71.947 mol) of compound b (molar ratio of compound a and compound b is 50:50),
At the same time, 29.107 kg (143.89 mol) of dibutyl oxalate was supplied into the reaction vessel at a flow rate of 1.49 liters / minute over about 17 minutes by a diaphragm pump.
The internal pressure in the pressure vessel immediately after the supply increased to 0.35 MPa by butanol generated by the polycondensation reaction, and the temperature of the polycondensate increased to about 170 ° C.
Thereafter, the temperature was raised to 260 ° C. over 1.5 hours.
Meanwhile, the internal pressure was adjusted to 0.5 MPa while extracting the generated butanol from the pressure relief port.
Immediately after the temperature of the polycondensate reached 260 ° C., butanol was extracted from the pressure release port over about 20 minutes, and the internal pressure was brought to normal pressure.
The temperature was raised from normal pressure while flowing nitrogen gas at 1.5 liters / minute, and the temperature of the polycondensate was changed to 275 ° C. over about 1 hour, and the reaction was carried out at 275 ° C. for 3 hours.
Thereafter, the stirring was stopped and the system was pressurized to 1 MPa with nitrogen and allowed to stand for about 10 minutes. Then, the pressure was released to an internal pressure of 0.1 MPa, and the polycondensate was extracted in a string form from the lower outlet of the pressure vessel.
The string-like polymer was immediately cooled with water, and the water-cooled string-like resin was pelletized with a pelletizer.
The obtained polyamide was a white tough polymer, and ηr = 2.61.

(6) Examples 6 and 7
100 parts by mass of PX6-1 and PX6-5 pellets were kneaded in a twin screw extruder with a 44 mmφ vent set to a barrel temperature of 340 and 300 ° C., respectively.
When this polyamide resin is kneaded, glass fiber (fiber diameter 11 μm, fiber cut length 3 mm) is supplied from the middle of the extruder to 43 parts by mass with respect to 100 parts by mass of the polyamide resin, and the desired solid injection is performed. Pellets that were polyamide resin compositions for molding were prepared.

(7) Comparative Example 1: (Polyamide resin: PX6-6)
(I) Pre-polycondensation step: The inside of a 1 L separable flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a raw material inlet is replaced with nitrogen gas having a purity of 99.9999%.
500 ml of dehydrated toluene,
1,6-hexanediamine 58.7209 g (0.5053 mol) was charged.
After this separable flask was placed in an oil bath and heated to 50 ° C,
Dibutyl oxalate (102.1956 g, 0.5053 mol) was charged.
Next, the temperature of the oil bath was raised to 130 ° C., and the reaction was carried out for 5 hours under reflux.
Note that all operations from preparation of raw materials to completion of the reaction were performed under a nitrogen stream of 50 ml / min.
(Ii) Post-polycondensation step: The prepolymer obtained by the above operation is charged into a glass reaction tube having a diameter of about 35 mmφ equipped with a stirrer, an air cooling tube, and a nitrogen introduction tube, and the pressure inside the reaction tube is reduced to 13.3 Pa or less. Then, the operation of introducing nitrogen gas to normal pressure was repeated 5 times, and then the mixture was transferred to a salt bath maintained at 290 ° C. under a nitrogen stream of 50 ml / min. After the temperature of the salt bath was set to 340 ° C. over 1 hour, the pressure in the container was reduced to about 66.5 Pa, and the reaction was further continued for 2 hours.
Subsequently, after introducing nitrogen gas to normal pressure, it was removed from the salt bath and cooled to room temperature under a nitrogen stream of 50 ml / min to obtain a polyamide resin.
The obtained polymer was a yellow polymer, and ηr = 1.65.

(8) Comparative examples 2 and 3
As a polyamide resin of a resin composition for injection molding,
Nylon 6 (Ube Industries, UBE nylon 1015B: PA6) (Comparative Example 2) and nylon 66 (Ube Industries, UBE nylon 2020B: PA66) (Comparative Example 3) pellets were used.

(9) Comparative Example 4
PX6-5 of Example 7 was replaced with PA6, and a pellet which was a polyamide resin composition for injection molding containing glass fibers under the same conditions as in Example 7 was produced.

For the polyamide resins and resin compositions in Examples 1 to 7 and Comparative Examples 1 to 4, relative viscosity, melt viscosity, melting point, 1% weight loss temperature, saturated water absorption, chemical resistance, hydrolysis resistance, dry and wet The physical properties of
For Examples 1 to 7 and Comparative Examples 2 and 4, warpage was measured under the conditions described below.
The results are shown in Table 1.

(10) Example 8
An intake manifold and a fuel injection were manufactured by injection molding using the resin compositions of Examples 1 to 7 and Comparative Examples 1 to 4.
The polyamide resin compositions for injection molding of Examples 1 to 7 had moldability equivalent to or higher than that of PA6 and PA66.

[Physical property measurement, molding, evaluation conditions]
The following contents were used.

(1) Relative viscosity ηr of polyamide resin
ηr was measured at 25 ° C. using an Ostwald viscometer using a 96% sulfuric acid solution (concentration: 1.0 g / dl) of each polyamide resin of Examples 1 to 5 and Comparative Examples 1, 2 and 4.

(2) Melt Viscosity of Polyamide Resin The melt viscosities of the polyamide resins of Examples 1 to 5 and Comparative Examples 1 and 2 are 25 mm cone plates in a melt viscoelasticity measuring device ARES manufactured by TA Instruments Japan. In the nitrogen,
340 ° C. when PA 6-1 to 2 and 6 are included as the polyamide resin,
300 ° C. when PA 6-3 is included as the polyamide resin,
260 ° C when PA6 is included as the polyamide resin,
Measurement was performed under conditions of a shear rate of 0.1 s- ¹ .

(3) Melting point of polyamide resin (Tm)
Tm of each polyamide resin of Examples 1 to 5 and Comparative Examples 1 to 3 was measured under a nitrogen atmosphere using PYRIS Diamond DSC manufactured by PerkinELmer.
Tm when PA 6-1 to 2 and 6 are included as the polyamide resin is
The temperature is raised from 30 ° C. to 350 ° C. at a rate of 10 ° C./min (referred to as a temperature rise first run),
After holding at 350 ° C for 3 minutes,
The temperature is decreased to -100 ° C at a rate of 10 ° C / min (referred to as a temperature decrease first run),
Next, the temperature was raised to 350 ° C. at a rate of 10 ° C./min (referred to as a temperature raised second run).
Tm when PA6-3-5, PA6 and PA66 are included as the polyamide resin is
The temperature is increased from 30 ° C. to 310 ° C. at a rate of 10 ° C./min (referred to as a temperature rising first run),
After holding at 310 ° C for 3 minutes,
The temperature is decreased to -100 ° C at a rate of 10 ° C / min (referred to as a temperature decrease first run),
Next, the temperature was raised to 310 ° C. at a rate of 10 ° C./min (referred to as a temperature rise second run).
The endothermic peak temperature of the elevated temperature second run was defined as Tm.

(4) 1% weight loss temperature Td of polyamide resin
Td of each polyamide resin of Examples 1 to 7 and Comparative Examples 1 to 4 was measured by thermogravimetric analysis (TGA) using THERMOGRAVIMETRIC ANALYZER TGA-50 manufactured by Shimadzu Corporation.
The temperature was raised from room temperature to 500 ° C. at a rate of 10 ° C./min under a nitrogen stream of 20 ml / min, and Td was measured.

(5) Test Film and Plate Molding Conditions (5-1) Test Film Each polyamide of Examples 1 to 5 and Comparative Examples 1 to 3 was formed using a vacuum press machine TMB-10 manufactured by Toho Machinery Co., Ltd. A film for test of saturated water absorption, chemical resistance, hydrolysis resistance and water absorption of the resin was obtained.
Under a reduced pressure atmosphere of 500 to 700 Pa,
340 ° C. when PA 6-1 to 2 and 6 are included as the polyamide resin,
300 ° C. when PA 6-3 is included as the polyamide resin,
260 ° C when PA6 is included as the polyamide resin,
When PA66 is included as a polyamide resin,
After 5 minutes of heating and melting,
The film was formed by pressing at 5 MPa for 1 minute.
Next, the reduced-pressure atmosphere was returned to normal pressure, and then cooled and crystallized at room temperature of 5 MPa for 1 minute to obtain a test film.

(5-2) Test plate Resin temperature 340 ° C. when PA6-1-2 and 6 are included as the polyamide resin,
300 ° C. when PA 6-3 is included as the polyamide resin,
260 ° C when PA6 is included as the polyamide resin,
When PA66 is included as a polyamide resin,
A test plate was obtained by injection molding at a mold temperature of 80 ° C.
The injection molding conditions were: injection pressure: primary pressure 650 kg / cm ² , injection time: 11 seconds, cooling time: 20 seconds.

(6) Saturated water absorption rate of polyamide resin A test film (dimensions: 20 mm × 10 mm, thickness 0.25 mm; mass about 0.05 g) is immersed in ion-exchanged water at 23 ° C.
The test film was taken out every predetermined time, and the mass of the film was measured.
When the rate of increase in the mass of the test film lasts 3 times within the range of 0.2%, it is judged that the absorption of moisture into the test film has reached saturation,
The saturated water absorption (%) was calculated by the following formula (1) from the mass (Xg) of the test film before being immersed in water and the mass (Yg) of the test film when saturation was reached.
Saturated water absorption (%) = 100 × (Y−X) / X (1)

(7) Chemical resistance of polyamide resin After the test film (dimensions: 20 mm × 10 mm, thickness 0.25 mm; mass about 0.05 g) was immersed in the chemicals listed below for 7 days, the weight residual ratio of the film (%) And changes in appearance were observed. Tests were conducted on samples immersed in concentrated hydrochloric acid, 64% sulfuric acid, 30% NaOH aqueous solution, and 5% K ₂ MnO ₄ at 23 ° C. and benzyl alcohol at 50 ° C.

(8) Hydrolysis resistance of polyamide resin A test film (dimensions: 20 mm × 10 mm, thickness 0.25 mm; mass about 0.05 g) was placed in an autoclave, and water (pH = 7), 0.5 mol / l The weight residual ratio (%) and appearance change after treatment for 60 minutes at 121 ° C. in sulfuric acid (pH = 1) or 1 mol / l sodium hydroxide aqueous solution (pH = 14) were examined.

(9) Mechanical properties of polyamide resin
What was evaluated at 23 ° C. without conditioning immediately after molding was dried,
What was evaluated at 23 ° C. after conditioning at a humidity of 65% and a temperature of 23 ° C. after molding was described in the table as wet.

(9-1) Tensile strength: Measured according to ASTM D638 using a test plate formed into a dumbbell shape of a Type I test piece described in ASTM D638.
(9-2) Flexural modulus: Measured according to ASTM D790 using a test plate.
(9-3) Deflection temperature under load (thermal deformation temperature): Measured with a load of 1.82 MPa in accordance with ASTM D648 using a test plate.

(10) Water absorption rate of polyamide resin Except that it was placed under conditions of 23 ° C. and humidity 65% RH using a test film (dimensions: 20 mm × 10 mm, thickness 0.25 mm; mass about 0.05 g). (6) The water absorption rate (equilibrium water absorption rate) (%) was calculated according to the method for measuring the saturated water absorption rate.

(11) Warpage of injection molded article The injection molded article of Fig. 1 was produced under the following injection conditions using the pellets obtained in Examples 1 to 7 and Comparative Examples 2 and 4, and then 23 ° C and relative humidity 65. The warpage after 10 days from the production was measured.

(11-1) Injection molding conditions / Injection molding machine: IS-80 manufactured by Toshiba Machine Co., Ltd.
Cylinder setting temperature When PA6-1 and 2 and 6 are included as polyamide resin C1 300 ° C; C2 340 ° C; C3 340 ° C; C4 340 ° C
Nozzle heater set temperature 340 ℃
When PA6-3-5 and 6 and PA6 are included as polyamide resin C1 260 ° C; C2 300 ° C; C3 300 ° C; C4 300 ° C
Nozzle heater set temperature 300 ℃
Injection pressure: Primary pressure 650 kg / cm ²
-Mold temperature: Moving mold 40 ° C; Fixed mold 40 ° C
・ Injection time: 11 seconds ・ Cooling time: 20 seconds

(11-2) Evaluation conditions for warpage Dimension A and B in FIG.
Warpage (warping of inward tilt) (%) = (B length−A length) / B length × 100

From Table 1, the polyamide resin composition for injection molding of the present invention has low water absorption compared to materials such as nylon 6 and nylon 66, is excellent in chemical resistance and hydrolysis resistance, and is a machine under wet conditions. Excellent physical properties, has a wider moldable temperature range than polyamide resin (PX6-6) using 1,6-hexanediamine alone as a diamine component, has excellent melt moldability, and can have a higher molecular weight. It can be seen that a tough injection-molded product with reduced warpage can be produced even when glass fiber, which is said to have a large warpage and low dimensional stability, is added.
In addition, the polyamide resin composition using PX6-6 could not be melt-kneaded and molded because Td-Tm was small.

Claims (2)

A polyamide resin composition for injection molding containing a polyamide resin (component A),
The component A is composed of a unit derived from a dicarboxylic acid and a unit derived from a diamine,
The dicarboxylic acid comprises oxalic acid (compound a);
The diamine comprises 1,6-hexanediamine (compound b) and 2-methyl-1,5-pentanediamine (compound c);
A polyamide resin composition for injection molding, wherein the molar ratio of the compound b to the compound c is 99: 1 to 50:50.   An injection molded article obtained by injection molding the polyamide resin composition for injection molding according to claim 1.

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