JP2012107135A - Polyamide resin composition and molded article comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin composition giving a molded article exhibiting uniform thermal conductivity, which can be stably produced by a general kneader without opening the head part of an extruder (kneader).SOLUTION: The polyamide resin composition includes a polyamide resin (A) and a metal oxide particle (B), wherein the metal oxide particle (B) contains 10-50 mass% of one having particle diameters of 70 μm or larger, and contains 1-50 mass% of one having 20 μm or less, based on the total amount thereof, and the metal oxide particle (B) is contained by 70-85 mass% in the polyamide resin composition.

Description

  The present invention relates to a polyamide resin composition excellent in thermal conductivity and a molded article comprising the same.

When magnesium oxide is blended with a thermoplastic resin, the thermal conductivity is improved according to the amount, but adding a large amount of unmelted magnesium oxide to the thermoplastic resin by melt-kneading means that the molten thermoplastic resin Since the ratio decreases, it is difficult to maintain productivity with a single-screw or twin-screw extruder. Patent Document 1 discloses that as a method for stably and highly filling the conductive filler, kneading in a state where the head portion of the extruder is opened, the conductive material is opened without opening the head portion of the extruder. There is no disclosure of a method for stably and highly filling a conductive filler.
Patent Document 2 discloses a method for improving moldability, appearance, and thermal conductivity by blending a specific amount of magnesium oxide having a specific particle diameter, but the thermal conductivity varies depending on the measurement position of the molded product. There is no disclosure about stably obtaining a molded product showing a uniform thermal conductivity regardless of the measurement position.

Japanese Patent Laid-Open No. 8-1663 Japanese Patent Laid-Open No. 3-81366

  An object of the present invention is to provide a polyamide resin that can be stably produced by a general kneader without opening the head portion of an extruder (kneader), and a molded product having uniform thermal conductivity can be obtained. It is to provide a composition.

The above problems are solved by the present invention described below.
That is, the present invention is a polyamide resin composition comprising a polyamide resin (A) and metal oxide particles (B),
The metal oxide particles (B) contain 10% by mass or more and 50% by mass or less of particles having a particle size of 70 μm or more and 1% by mass or more and 50% by mass or less of particles having a particle size of 20 μm or less with respect to the total amount. Including
The present invention relates to a polyamide resin composition containing 70% by mass or more and 85% by mass or less of metal oxide particles (B) with respect to the polyamide resin composition.

  According to the present invention, it is possible to provide a polyamide resin composition that can be stably produced with a general kneader without opening the head portion of the kneader, and that can provide a molded product exhibiting uniform thermal conductivity.

It is the figure which showed the measurement location of the thermal conductivity for evaluating thermal conductivity.

The present invention is a polyamide resin composition comprising a polyamide resin (A) and metal oxide particles (B),
The metal oxide particles (B) contain 10% by mass or more and 50% by mass or less of particles having a particle size of 70 μm or more and 1% by mass or more and 50% by mass or less of particles having a particle size of 20 μm or less with respect to the total amount. Including
A polyamide resin composition containing 70% by mass or more and 85% by mass or less of metal oxide particles (B) with respect to the polyamide resin composition.

[Polyamide resin (A)]
The polyamide resin (A) used in the present invention is obtained by polymerization or copolymerization by a known method such as melt polymerization, solution polymerization or solid phase polymerization. Specifically, polycaprolactam (polyamide 6), Polyundecan lactam (polyamide 11), polydodecan lactam (polyamide 12), polyethylene adipamide (polyamide 26), polytetramethylene adipamide (polyamide 46), polyhexamethylene adipamide (polyamide 66), polyhexamethylene Azeramide (polyamide 69), polyhexamethylene sebamide (polyamide 610), polyhexamethylene undecamide (polyamide 611), polyhexamethylene dodecamide (polyamide 612), polyhexamethylene terephthalamide (polyamide 6T), poly Hexamethylene Phthalamide (Polyamide 6I), Polyhexamethylene hexahydroterephthalamide (Polyamide 6T (H)), Polynonamethylene adipamide (Polyamide 96), Polynonamethylene azelamide (Polyamide 99), Polynonamethylene sebacamide ( Polyamide 910), polynonamethylene dodecamide (polyamide 912), polynonamethylene terephthalamide (polyamide 9T), polytrimethylhexamethylene terephthalamide (polyamide TMHT), polynonamethylene hexahydroterephthalamide (polyamide 9T (H )), Polynonamethylenenaphthalamide (polyamide 9N), polydecamethylene adipamide (polyamide 106), polydecamethylene azelamide (polyamide 109), polydecamethylene decamide (polyamide 1010), Ridecamemethylene dodecamide (polyamide 1012), polydecamethylene terephthalamide (polyamide 10T), polydecamethylene hexahydroterephthalamide (polyamide 10T (H)), polydecamethylene naphthalamide (polyamide 10N), polydodecamethylene Adipamide (polyamide 126), polydodecamethylene azeamide (polyamide 129), polydodecamethylene sebamide (polyamide 1210), polydodecamethylene dodecamide (polyamide 1212), polydodecamethylene terephthalamide (polyamide 12T), Polydodecamethylene hexahydroterephthalamide (Polyamide 12T (H)), Polydodecamethylene naphthalamide (Polyamide 12N), Polymetaxylylene adipamide (Polyamide MXD6), Polymetaxy Rilensberamide (Polyamide MXD8), Polymetaxylylene Azelamide (Polyamide MXD9), Polymetaxylylene Sebamide (Polyamide MXD10), Polymetaxylylene decanamide (Polyamide MXD12), Polymetaxylylene terephthalamide (Polyamide MXDT), Polymetax Silylene isophthalamide (polyamide MXDI), polymetaxylylene naphthalamide (polyamide MXDN), polybis (4-aminocyclohexyl) methane dodecamide (polyamide PACM12), polybis (4-aminocyclohexyl) methane terephthalamide (polyamide PACMT), Polybis (4-aminocyclohexyl) methane isophthalamide (polyamide PACMI), polybis (3-methyl-4-aminocyclohexyl) methand Examples include decamide (polyamide dimethyl PACM12), polyisophorone adipamide (polyamide IPD6), polyisophorone terephthalamide (polyamide IPDT), and polyamide copolymers using these raw material monomers. These can use 1 type (s) or 2 or more types. Among these, polyamide 6, polyamide 12, polyamide 66, polyamide 6/66 copolymer (copolymer of polyamide 6 and polyamide 66, hereinafter the copolymer is also described), polyamide 6/69 copolymer, Polyamide 6/610 copolymer, polyamide 6/611 copolymer, polyamide 6/612 copolymer, polyamide 6/12 copolymer, polyamide 6/66/12 copolymer, polyamide 6 / IPD6 copolymer, Polyamide MXD6 is preferable, polyamide 6, polyamide 12, polyamide 66, polyamide 6/66 copolymer, polyamide 6/12 copolymer, polyamide 6 / IPD6 copolymer, polyamide 6/66/12 copolymer More preferably, it is polyamide 6, polyamide 66, polyamide 6/66 copolymer. But more preferably, from the viewpoint of moldability, the polyamide 6 is particularly preferred.

  There are no particular restrictions on the type and concentration or molecular weight distribution of the end group of the polyamide resin (A) of the present invention, and molecular weight regulators such as acetic acid and stearic acid are used for molecular weight adjustment and melt stabilization during molding processing. One or more of diamines such as monocarboxylic acid, metaxylylenediamine and isophoronediamine, monoamine and dicarboxylic acid can be added in appropriate combination.

  The polyamide resin (A) is produced by kneading reaction extrusion such as batch reaction kettle, one tank type or multi tank type continuous reaction apparatus, tubular continuous reaction apparatus, uniaxial kneading extruder, biaxial kneading extruder, etc. It can be manufactured by a polyamide manufacturing apparatus such as a machine. Examples of the polymerization method include melt polymerization, solution polymerization, and solid phase polymerization. In these polymerization methods, polymerization can be carried out by repeating normal pressure, reduced pressure, and pressure operation, and they can be used alone or in appropriate combination.

  According to JIS K-6920, the relative viscosity of the polyamide resin (A) measured under the conditions of 96% by mass sulfuric acid, 1% by mass polyamide concentration and 25 ° C. temperature is 1.5 to 5.0. It is preferable that it is 1.7 or more and 4.5 or less. If the relative viscosity of the polyamide resin is less than the above value, the mechanical properties of the obtained molded product may be lowered. On the other hand, when the above value is exceeded, the viscosity at the time of melting increases, and it may be difficult to mold the molded product. Furthermore, from the viewpoint of the productivity of the polyamide resin composition of the present invention and the moldability of the molded product, it is more preferably 1.7 or more and 3.0 or less.

  Further, the amount of water extracted from the polyamide resin (A) measured according to the method for measuring the content of low molecular weight substances specified in JIS K-6920 is not particularly limited. It is preferable that the amount be 5% by mass or less because there is a possibility that the productivity may be deteriorated due to adhesion to manufacturing equipment, or the appearance may be deteriorated due to adhesion to product pellets.

  The particle shape of the polyamide resin (A) is preferably a powder form having an average particle diameter of 1 mm or less from the viewpoint of uniformly mixing the metal oxide particles (B) and other additives. In addition, there is no restriction | limiting in particular as the method of making it into a powder form, However, Freezing grinding | pulverization is preferable from a viewpoint of the productivity of powder.

  In the polyamide resin (A) of the present invention, various additives and modifiers that are usually blended within a range that does not impair the properties of the resulting molded product, such as a heat stabilizer, an ultraviolet absorber, and a light stabilizer. , Antioxidants, antistatic agents, lubricants, antiblocking agents, fillers, tackifiers, sealability improvers, antifogging agents, crystal nucleating agents, mold release agents, plasticizers, crosslinking agents, foaming agents, colorants (Pigments, dyes, etc.) can be added, and the addition method is not particularly limited, and various conventionally known methods can be employed. For example, it can be added by a dry blending method, a melt kneading method or the like together with other components blended as necessary. The melt kneading can be performed using a kneader such as a single screw extruder, a twin screw extruder, a kneader, or a Banbury mixer.

  It is preferable that the compounding quantity of a polyamide resin (A) is 15 to 30 mass% with respect to a polyamide resin composition. When the amount is less than 15% by mass, the resin component becomes brittle due to a decrease in the resin component, and thus it becomes difficult to pelletize the strands during kneading. Furthermore, when the melting component (resin component) at the time of kneading decreases, the fluidity decreases and the kneading property also deteriorates. Moreover, when it exceeds 30 mass%, since the compounding quantity of a metal oxide particle (B) decreases, heat conductivity cannot fully be exhibited. From the viewpoint of kneadability and thermal conductivity, the blending amount of the polyamide resin (A) is preferably 14.9% by mass or more and 29.9% by mass or less, and more preferably 20% by mass or more and 25% by mass or less.

[Metal oxide particles (B)]
Examples of the metal oxide particles (B) used in the present invention include particles such as aluminum oxide, magnesium oxide, beryllium oxide, and titanium oxide. From the viewpoint of electrical insulation and thermal conductivity, aluminum oxide, and Magnesium oxide is preferable, and magnesium oxide is more preferable.

  The metal oxide particles (B) used are those processed into a powder form, and the average particle diameter is not particularly limited. However, when the average particle diameter is less than 0.5 μm, the moisture in the air is increased by increasing the surface area. When the average particle diameter exceeds 300 μm, the mechanical strength typified by impact strength tends to decrease, and magnesium oxide is exposed on the surface of the molded product and surface properties may deteriorate. Therefore, the average particle size is preferably 0.5 μm or more and 300 μm or less, more preferably 12 μm or more and 73 μm or less, and further preferably 30 μm or more and 60 μm or less.

  The metal oxide particles (B) contain 10% by mass or more and 50% by mass or less of particles having a particle diameter of 70 μm or more with respect to the total amount, and 10% by mass or more and 30% by mass from the viewpoint of physical properties such as impact resistance. It is preferably included below, and those having a particle size of 20 μm or less are contained in an amount of 1% by mass to 50% by mass, and from the viewpoint of stability of raw material transfer such as a raw material feed during kneading, 15% by mass to 45% by mass It is more preferable. Furthermore, the metal oxide particles preferably contain 40% by mass or more and 70% by mass or less of metal oxide particles having a particle diameter of more than 20 μm and less than 70 μm from the viewpoints of physical properties such as impact resistance and kneadability. More preferably, the content is 52% by mass or less.

  Moreover, the purity of the metal oxide particles (B) is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more from the viewpoint of thermal conductivity. preferable.

  The compounding amount of the metal oxide particles (B) is 70% by mass or more and 85% by mass or less with respect to the polyamide resin composition. When the amount is less than 70% by mass, the thermal conductivity is sufficiently increased by increasing the resin amount. I can't show it. When the amount exceeds 85% by mass, the strand becomes brittle due to a decrease in the amount of the resin, so that it becomes difficult to pelletize the strand during kneading. 70 mass% or more and 85 mass% or less are preferable from a viewpoint of heat conductivity and kneadability, and 75 mass% or more and 85 mass% or less are more preferable.

[Polyhydric alcohol (C)]
The polyhydric alcohol used in the present invention is not particularly limited, but those having a melting point of 150 ° C. or higher and 280 ° C. or lower are preferable. The melting point means the temperature of the endothermic peak (melting point) as measured by differential scanning calorimetry (DSC) used for measuring the melting point and freezing point of the resin. Examples of the polyhydric alcohol (C) having a melting point of 150 ° C. or higher and 280 ° C. or lower include pentaerythritol, dipentaerythritol, trimethylolethane, and the like, and these can be used in combination. From the viewpoints of kneadability and moldability, pentaerythritol and / or dipentaerythritol is preferable.

  Moreover, it is preferable that the compounding quantity of a polyhydric alcohol is 0.1 to 5 mass% from a viewpoint of kneadability or moldability. From the viewpoint of securing fluidity during molding and suppressing generated gas, it is more preferably 0.5% by mass or more and 3% by mass or less.

[Polyamide resin composition]
The method for producing the polyamide resin composition of the present invention is not particularly limited as long as it is a melt-kneading method, and various conventionally known methods can be employed. For example, it can be produced using a kneader such as a single screw extruder, a twin screw extruder, a kneader, or a Banbury mixer. Among these, the polyamide resin composition of the present invention can be suitably produced using a single screw extruder or a twin screw extruder.

  In addition, the polyamide resin of the present invention includes various additives and modifiers that are usually blended within a range that does not impair the properties of the obtained molded product, such as a heat stabilizer, an ultraviolet absorber, a light stabilizer, Add antioxidants, antistatic agents, lubricants, antiblocking agents, fillers, antifogging agents, crystal nucleating agents, mold release agents, plasticizers, crosslinking agents, foaming agents, colorants (pigments, dyes, etc.), etc. The addition method is not particularly limited, and various conventionally known methods can be adopted in addition to the above production method. For example, the method of dry blending is mentioned.

  As a method for molding the obtained polyamide resin composition into a molded product, molding methods such as injection, extrusion, pressing, and the like are possible. By these molding methods, it can be processed into a molded product, a sheet or the like.

  The thermal conductivity of the molded product obtained from the polyamide resin of the present invention is measured according to JIS R-2616, and the difference between the maximum value and the minimum value, that is, the difference in thermal conductivity within the molded product is 0. It is preferably within 5 W / m · K.

  Molded articles using the polyamide-based resin composition of the present invention include various molded articles, sheets, films, etc., for which molded articles of polyamide resin compositions have been conventionally used, computers and related equipment, optical equipment. It can be used for a wide range of applications such as electrical / electronic equipment, information / communication equipment, precision equipment, civil engineering / building supplies, medical supplies, and household goods. In particular, it is useful for applications such as automobiles and electrical / electronic devices.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples without departing from the gist of the present invention. The raw materials used and various evaluation methods are shown below.

(Raw materials used)
[Polyamide resin (A)]
Polyamide resin (a-1): Polyamide 6 (P1011F manufactured by Ube Industries, Ltd., a powder having an average particle diameter of 1 mm or less that passes through a 12 mesh screen mesh, a relative viscosity of 2.22, a water extraction amount of 0.3% by mass, Specific gravity 1.14)

[Metal oxide particles (B)]
Magnesium oxide (b-1): Magnesium oxide (Ube Materials Co., Ltd., RF-70C-SC, average particle diameter 7 μm, purity 99%)
Magnesium oxide (b-2): Magnesium oxide (Ube Materials Co., Ltd., RF-50-SC, average particle size 53 μm, purity 98%)
Magnesium oxide (b-3): Magnesium oxide (Ube Materials Co., Ltd., RF-10C-SC, average particle size 72 μm, purity 99%)

[Polyhydric alcohol (C)]
Pentaerythritol (c-1) (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., melting point: 260 ° C., specific gravity 1.4)

(Evaluation methods)
(1) Kneadability Kneadability was determined by using a TEX44 having a diameter of 44 mmΦ and an L / D of 35, which is a same-direction biaxial kneader manufactured by Nippon Steel Co., Ltd. The following x and o were used to determine whether the polyamide resin composition was produced under a kneading condition of about 3 minutes / hr.
X: The strand discharged from the kneader is fragile, the strand breaks and cannot be pelletized continuously for 1 hour or more. Or, the kneading load is large and exceeds the upper limit of the allowable current load of the kneading machine of 150A.
○: Can be pelletized continuously for 1 hour or more and kneading load does not exceed 150A.

(2) Thermal conductivity Thermal conductivity was measured according to JIS R-2616. (Unsteady hot wire probe method)
The test piece used was 150 mm × 150 mm × 3 mmt and measured at three locations. The vicinity of the gate shown in FIG.
The difference in thermal conductivity was defined as the difference between the maximum value and the minimum value of the thermal conductivity measured at three locations.

Example 1
Polyamide resin (a-1) 23.2% by mass of P1011F manufactured by Ube Industries, Ltd., magnesium oxide (b-1) 7.6% by mass of RF-70C-SC manufactured by Ube Materials Co., Ltd., magnesium oxide (b- 2) 37.9% by mass of RF-50-SC manufactured by Ube Materials Co., Ltd., magnesium oxide (b-3) 30.3% by mass of RF-10C-SC manufactured by Ube Materials Co., Ltd., pentaerythritol (c- 1) was blended to 1.0% by mass.
The particle size of magnesium oxide was measured according to JIS R 1629, and the particle size distribution of magnesium oxide (b-1), magnesium oxide (b-2), and magnesium oxide (b-2) was measured by a laser diffraction scattering method. From the results and the respective blending ratios, the blending ratio of magnesium oxide having a particle diameter of 20 μm or less and 70 μm or more with respect to the total amount of magnesium oxide was calculated.
The blended magnesium oxide had an average particle diameter of 37 μm, the blending ratio of magnesium oxide having a particle diameter of 70 μm or more was 15 mass%, and the blending ratio of magnesium oxide of 20 μm or less was 41 mass%.
(The blending ratio of magnesium oxide whose particle diameter is twice or more the average particle diameter was 11% by mass, and the blending ratio of magnesium oxide having a particle size of half or less of the average particle diameter was 41% by mass.)
These are put into a cylindrical mixer, mixed, the mixture is introduced into TEX44 which is a kneader manufactured by Nippon Steel Co., Ltd., melt-kneaded at a set temperature of 290 ° C., a screw speed of 200 rpm, and a discharge rate of 20 kg / hr, The kneadability was evaluated during melt kneading. In addition, a test piece of 150 mm × 150 mm × 3 mm was prepared for thermal conductivity by injection molding of the obtained polyamide resin composition pellets under conditions of a cylinder temperature of 290 ° C., a mold temperature of 80 ° C., and a cooling time of 20 seconds. . The thermal conductivity of the measurement locations A, B, and C was evaluated using the prepared test piece. The results are shown in Table 1.

Example 2
In Example 1, magnesium oxide (b-1) RF-70C-SC made by Ube Materials Co., Ltd. was 30.3% by mass, magnesium oxide (b-2) RF-50-SC made by Ube Materials Co., Ltd. was 37 .9% by mass, magnesium oxide (b-3) Polyamide resin composition pellets were produced in the same manner as in Example 1, except that RF-10C-SC manufactured by Ube Materials Co., Ltd. was changed to 7.6% by mass. These were evaluated. The results are shown in Table 1.
The blended magnesium oxide has an average particle diameter of 52 μm, and the blending ratio of magnesium oxide having a particle diameter of 70 μm or more is 30% by mass, and the blending ratio of magnesium oxide having a particle diameter of 20 μm or less is 21% by mass with respect to the total blended magnesium oxide. Become.
(The blending ratio of magnesium oxide whose particle diameter is twice or more the average particle diameter is 15% by mass, and the blending ratio of magnesium oxide whose particle diameter is half or less of the average particle diameter is 24% by mass.)

Example 3
In Example 1, 15.2% by mass of magnesium oxide (b-1) Ube Materials Co., Ltd. RF-70C-SC, 15.2% by mass, magnesium oxide (b-2) 45 of Ube Materials Co., Ltd. RF-50-SC .5% by mass, magnesium oxide (b-3) Polyamide resin composition pellets were produced in the same manner as in Example 1 except that RF-10C-SC manufactured by Ube Materials Co., Ltd. was changed to 15.2% by mass. These were evaluated. The results are shown in Table 1.
The average particle diameter of the blended magnesium oxide is 48 μm, and the magnesium oxide having a particle diameter of 70 μm or more is 22% by mass and the magnesium oxide having a particle diameter of 20 μm or less is 25% by mass with respect to the total amount of the mixed magnesium oxide.
(The blending ratio of magnesium oxide whose particle diameter is twice or more of the average particle diameter is 10% by mass, and the blending ratio of magnesium oxide whose particle diameter is half or less of the average particle diameter is 26% by mass.)

Comparative Example 1
Polyamide resin (a-1) 23.2% P1011F manufactured by Ube Industries, Ltd., magnesium oxide (b-2) 75.9% by mass of RF-50-SC manufactured by Ube Materials, Inc., pentaerythritol (c-1) ) Was prepared in the same manner as in Example 1 except that it was blended to 1.0% by mass, and these were evaluated. The results are shown in Table 1.
The average particle diameter of the mixed magnesium oxide is 52 μm, and the mixing ratio of magnesium oxide having a particle diameter of 70 μm or more is 20 mass% and the mixing ratio of magnesium oxide of 20 μm or less is 0.0 mass with respect to the total mixed magnesium oxide. %.
(The blending ratio of magnesium oxide whose particle diameter is twice or more of the average particle diameter is 2% by mass, and the blending ratio of magnesium oxide whose particle diameter is half or less of the average particle diameter is 1% by mass.)

Comparative Example 2
Polyamide resin (a-1) 23.2% P1011F manufactured by Ube Industries, Ltd., magnesium oxide (b-2) 30.3% by mass of RF-50-SC manufactured by Ube Materials Co., Ltd., magnesium oxide (b-3) ) Polyamide resin composition as in Example 1 except that RF-10C-SC manufactured by Ube Materials Co., Ltd. was blended so as to be 45.5% by mass and pentaerythritol (c-1) was 1.0% by mass. Pellets were manufactured and evaluated. The results are shown in Table 1.
The average particle diameter of the mixed magnesium oxide is 11 μm, and the mixing ratio of magnesium oxide having a particle diameter of 70 μm or more is 8 mass% and the mixing ratio of magnesium oxide of 20 μm or less is 56 mass% with respect to the total mixed magnesium oxide. Become.
(The blending ratio of magnesium oxide having a particle size of twice or more the average particle diameter is 42% by mass, and the blending ratio of magnesium oxide having a particle size of half or less of the average particle size is 25% by mass.)

Comparative Example 3
Polyamide resin (a-1) 24.2% P1011F manufactured by Ube Industries, Ltd., magnesium oxide (b-1) 30.3% by mass of RF-70-SC manufactured by Ube Materials Co., Ltd., magnesium oxide (b-2) ) Example 1 except that Ube Materials Co., Ltd. RF-50-SC was 37.9% by mass and magnesium oxide (b-3) Ube Materials Co., Ltd. RF-10C-SC was 7.6% by mass. In the same manner, pellets of the polyamide resin composition were produced and evaluated. The results are shown in Table 1.
The average particle diameter of the mixed magnesium oxide is 52 μm, and the mixing ratio of the magnesium oxide having a particle diameter of 70 μm or more is 30.0% by mass and the mixing ratio of the magnesium oxide is 20 μm or less with respect to the total mixed magnesium oxide. 21.0% by mass.
(The blending ratio of magnesium oxide whose particle diameter is twice or more the average particle diameter is 15% by mass, and the blending ratio of magnesium oxide whose particle diameter is half or less of the average particle diameter is 24% by mass.)

Comparative Example 4
Magnesium oxide (b-1) 75.9% by mass of RF-70-SC manufactured by Ube Materials Co., Ltd., magnesium oxide (b-2) RF-50-SC manufactured by Ube Materials Co., Ltd. and magnesium oxide (b-3) ) Manufactured in the same manner as in Example except that Ube Materials Co., Ltd. was changed to 0% by mass, but the kneading state was poor and the pellet of polyamide resin composition could not be obtained.
The average particle diameter of the mixed magnesium oxide is 74 μm, and the mixing ratio of magnesium oxide having a particle diameter of 70 μm or more is 52.0 mass% and the mixing ratio of magnesium oxide of 20 μm or less is 30 with respect to the total amount of mixed magnesium oxide. 0.0% by mass. (The blending ratio of magnesium oxide whose particle diameter is twice or more of the average particle diameter is 16% by mass, and the blending ratio of magnesium oxide whose particle diameter is half or less of the average particle diameter is 37% by mass.)

Table 1

Claims (4)

A polyamide resin composition comprising a polyamide resin (A) and metal oxide particles (B),
The metal oxide particles (B) contain 10% by mass or more and 50% by mass or less of particles having a particle size of 70 μm or more and 1% by mass or more and 50% by mass or less of particles having a particle size of 20 μm or less with respect to the total amount. Including
The polyamide resin composition which contains 70 mass% or more and 85 mass% or less of metal oxide particles (B) with respect to a polyamide resin composition. Furthermore, the polyamide resin composition of Claim 1 which contains a polyhydric alcohol (C) 0.1-5 mass% with respect to a polyamide resin composition. The polyamide resin composition according to claim 1 or 2, wherein the metal oxide particles (B) are magnesium oxide.   The molded article which consists of a polyamide resin composition of any one of Claims 1-3.

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