JP2018070808A - Polyamide resin composition and molding thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin composition having high molding fluidity, and a good balance between toughness and flame retardancy, and a molding.SOLUTION: A polyamide resin composition contains (a) polyamide and (b) melamine cyanurate. In the (a) polyamide, the percentage of a component with a molecular weight of 15,000 or less, obtained by gel permeation chromatography (GPC), is 15.0-30.0 mass% of the whole of the (a) polyamide resin, and the percentage of a component with a molecular weight of 100,000 or more is 4.0-8.0 mass% of the whole of the (a) polyamide resin.SELECTED DRAWING: None

Description

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

  Polyamide resins have excellent properties in molding processability and the like including mechanical properties, and thus have been widely used for various parts such as automobile parts, electronic / electric parts, and industrial machine parts. Since it is particularly excellent in toughness, it is used in products having hinge parts such as connectors and clips. In many cases, these products require flame retardancy. In particular, it is desired to use a non-halogen flame retardant from an environmental viewpoint.

  A typical example of such a flame-retardant polyamide resin is a flame-retardant polyamide material using melamine cyanurate, and is used for, for example, connectors and clips in the field of electrical and electronic fields (see Patent Documents 1 and 2). ). Patent Document 3 proposes a polyamide resin composition using a specific phosphoric acid triester, a higher fatty acid metal salt, and a polyhydric alcohol.

JP 53-125959 A JP-A-53-031759 JP-A-11-106645

The flame-retardant polyamide resin using melamine cyanurate is filled in the composition in a form in which melamine cyanurate is not sufficiently compatible with the polyamide resin and is dispersed like an inorganic filler. For this reason, the polyamide resin composition filled with melamine cyanurate tends to have lower toughness.
This invention is made | formed in view of the said situation, and it aims at providing the polyamide resin composition which improved the flame retardance and toughness and reduced the toughness variation.

As a result of intensive studies to solve the above problems, the present inventor has improved the flame retardancy and toughness by setting the molecular weight component amount of the polyamide in the resin composition containing the polyamide and melamine cyanurate to a specific range, The inventors have found that the variation in toughness can be reduced, and have completed the present invention.
That is, the polyamide resin composition of the present invention is
A resin composition comprising (a) polyamide and (b) melamine cyanurate, wherein (a) the proportion of a component having a molecular weight of 15,000 or less obtained from gel permeation chromatography (GPC) in the polyamide is (A) It is 15.0-30.0 mass% of the whole polyamide, and the ratio of the component of molecular weight 100,000 or more is 4.0-8.0 mass% of (a) whole polyamide.

  (A) The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the polyamide is preferably 1.90 to 2.00.

  The polyamide resin composition of the present invention may further contain (c) a polyhydric alcohol and / or an ester derivative thereof.

  The polyamide resin composition of the present invention may further contain (d) a higher fatty acid metal salt.

  (A) It is preferable that 2-20 mass parts of (b) melamine cyanurate is included with respect to 100 mass parts of polyamide.

  The polyamide resin composition of the present invention comprises (a) 100 parts by mass of polyamide, (b) 2 to 20 parts by mass of melamine cyanurate, and (c) 0.1 to 1. It is preferable that 0 mass part is included.

  Further, (a) 100 parts by mass of polyamide, (b) 2 to 20 parts by mass of melamine cyanurate, and (d) 0.05 to 2.0 parts by mass of a higher fatty acid metal salt are preferably included.

  (A) 100 parts by mass of polyamide, (b) 2 to 20 parts by mass of melamine cyanurate, (c) 0.1 to 1.0 parts by mass of polyhydric alcohol and / or ester derivative thereof, and (d ) It is preferable to contain 0.05 to 2.0 parts by mass of a higher fatty acid metal salt.

  (A) Of the polyamides, 80% by mass or more is preferably polyamide 66.

  (A) The polyamide is more preferably polyamide 66.

  (A) The relative viscosity ηr of sulfuric acid of the polyamide 66 is preferably 2.65 to 2.88.

  (A) The relative viscosity ηr of sulfuric acid of the polyamide 66 is more preferably 2.73 to 2.88.

  The molded body of the present invention is formed by molding the polyamide resin composition of the present invention.

  The polyamide resin composition of the present invention is a polyamide resin composition comprising (a) polyamide and (b) melamine cyanurate, wherein (a) the molecular weight determined by gel permeation chromatography (GPC) in the polyamide resin The proportion of the component having a molecular weight of 15,000 or less is 15.0 to 30.0% by mass of (a) the whole polyamide, and the proportion of the component having a molecular weight of 100,000 or more is 4.0 of the whole polyamide (a). Since it is ˜8.0% by mass, the flame resistance and toughness are improved without affecting the mechanical properties, chemical resistance, good moldability, electrical properties, etc. inherent in the polyamide resin composition, and the toughness varies. It can be reduced, and can be suitably used for applications such as home appliance parts, electronic parts, and automobile parts.

FIG. 1 is a schematic top view of the hinge molded body used in the evaluation of the examples. FIG. 2 is a schematic side view of the hinge molded body used in the evaluation of the examples.

Hereinafter, the present invention will be described in detail.
[Polyamide resin composition]
The polyamide resin composition of the present invention is a resin composition containing (a) polyamide and (b) melamine cyanurate, and (a) a molecular weight determined from gel permeation chromatography (GPC) in the polyamide resin. The proportion of the component having a molecular weight of 15,000 or less is 15.0 to 30.0% by mass of (a) the whole polyamide, and the proportion of the component having a molecular weight of 100,000 or more is 4.0 of the whole polyamide (a). It is -8.0 mass%.
Hereinafter, each component will be described in detail.

[(A) component: polyamide]
The polyamide used in the present invention is a polymer having an amide bond (—NHCO—) in the main chain, such as polycaprolactam (polyamide 6), polytetramethylene adipamide (polyamide 46), polyhexamethylene. Adipamide (polyamide 66), polyhexamethylene cyclohexylamide (polyamide 6C), polyhexamethylene sebamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polyundecalactam (polyamide 11), polydodeca Lactam (polyamide 12), polyhexamethylene isophthalamide (polyamide 6I), polyhexamethylene terephthalamide (polyamide 6T), polynonanemethylene terephthalamide (polyamide 9T), polydodecamethylene terephthalamide Polyamide 12T), poly-m-xylylene adipamide (polyamide MXD6), and polyamide copolymers comprising at least two different polyamide forming components among these, and mixtures thereof, and the like.

  Among the various polyamides described above, the polyamide 66 is particularly suitable as a material for obtaining a part that has a high moldability and a high melting point and requires more heat resistance. In the case of using two or more kinds of polyamides, from the viewpoint of moldability and mechanical properties at high temperature, those containing 50 mass% or more of the polyamide 66 component are more preferable, and those containing 80 mass% or more are more preferable. 100 mass% is most preferable.

<Molecular weight of polyamide in composition>
The polyamide used in the polyamide resin composition of the present invention reduces flame retardancy, toughness, and toughness variation by setting the components having a molecular weight of 15,000 or less and the components having a molecular weight of 100,000 or more to specific amounts. be able to. Specifically, from the viewpoint of flame retardancy and molding stability, the component having a molecular weight of 15,000 or less is 15.0 to 30.0% by mass, and 15.0 to 20.0% by mass with respect to the entire polyamide. % Is more preferable. Further, from the viewpoint of flame retardancy and toughness, the component having a molecular weight of 100,000 or more is 4.0 to 8.0% by mass, and more preferably 4.5 to 8.0% by mass.

The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) is preferably 1.90 to 2.00 from the viewpoint of reducing variation in toughness and molding stability.
In order to set the molecular weight of the polyamide in the polyamide resin composition to a specific amount, for example, it is preferable to control the number of rotations of the screw and the screw configuration during melt kneading in an extruder.

  The molecular weight of the polyamide can be obtained by measurement using gel permeation chromatography (GPC). The apparatus is “HLC-8320GPC” manufactured by Tosoh Corporation, the detector is a differential refractometer (RI), the solvent is hexafluoroisopropanol (HFIP) in which 0.1 mol% of sodium trifluoroacetate is dissolved, Used 2 pieces of “TSKgel-GMHHR-M” and 1 piece of “G1000HHR” manufactured by Tosoh Corporation. The sample concentration was 1 to 3 (mg sample) / 1 (mL solvent), which was filtered with a filter to remove the insoluble matter, and used as a measurement sample. Based on the obtained elution curve, it computed by polymethylmethacrylate (PMMA) conversion.

<Viscosity of polyamide>
The polyamide preferably contains a polyamide having a 98% sulfuric acid relative viscosity ηr of 2.65 to 2.88, more preferably 2.73 to 2.88. By including such a polyamide, the obtained polyamide resin composition tends to be more excellent in the balance between flame retardancy and toughness. The 98% sulfuric acid relative viscosity ηr can be measured by the method described in Examples.

[(B) component: melamine cyanurate]
The (b) melamine cyanurate used in the present invention is an equimolar reaction product of melamine and cyanuric acid. For example, at a temperature of about 90 to 100 ° C., the melamine aqueous solution and the cyanuric acid aqueous solution are stirred and mixed to react. The product obtained in this manner is obtained by precipitation and filtration. The obtained product is a white solid and is preferably pulverized into a fine powder.

  In the present embodiment, the melamine cyanurate may contain 0.001% by mass or more and 0.30% by mass or less of unreacted melamine or cyanuric acid. Such melamine cyanurate is commercially available, and industrially available products can be used as appropriate.

The median diameter (D50) of (b) melamine cyanurate before mixing with the polyamide of component (a) is not particularly limited, but is preferably 1 μm to 20 μm from the viewpoint of dispersibility of melamine cyanurate, 1.5 μm to 15 μm is more preferable. When the median diameter of melamine cyanurate is 1 μm or more, handling becomes easy, and deterioration of cohesiveness of melamine cyanurate can be suppressed. When the median diameter of melamine cyanurate is 20 μm or less, the balance between dispersibility and handling in the polyamide resin composition is excellent.

  Here, as defined in JIS Z8901, the median diameter (D50) is when the mass of particles larger than a certain particle size occupies 50% of the mass of all granules in the particle size distribution of the granules. The particle diameter can be measured by, for example, a laser diffraction scattering method. Specifically, by the laser diffraction scattering method, the particle diameter is plotted on the horizontal axis and the frequency (mass) is plotted on the vertical axis, and the cumulative mass becomes 50% when the sum of the cumulative masses of these frequencies is 100%. It can be measured as the particle size.

  The compounding quantity of a melamine cyanurate is 2-20 mass parts with respect to 100 weight part of polyamides, Preferably it is 3-15 mass parts. The blending amount of melamine cyanurate is preferably 2 parts by mass or more from the viewpoint of flame retardancy and 20 parts by mass or less from the viewpoint of mechanical properties. Any known method can be applied to blending melamine cyanurate into the polyamide resin, but industrially, a method of kneading and blending with an extruder or the like is preferred.

[Component (c): Polyhydric alcohol and / or ester derivative thereof]
The polyhydric alcohol and / or ester derivative thereof used in the present invention preferably contains at least one polyalkylene polyhydric alcohol and fatty acid ester thereof. Glycols such as polyethylene glycol, polypropylene glycol, ethylene glycol, diethylene glycol, trimethylene glycol, propylene glycol, diols such as 1,4 butanediol, 1,5 pentadiol, 1,6 hexanediol, glycerin, pentaerythritol, etc. Examples of the polyhydric alcohols and fatty acid esters of polyalkylene polyhydric alcohols include polyalkylene polyhydric alcohols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, capric acid, lauric acid, myristic acid, palmitic acid, stearin. Examples include esters or derivatives thereof with aliphatic carboxylic acids such as acid, behenic acid, serotic acid, montanic acid, melicic acid, oleic acid and erucic acid. It is easily available in manner. From the viewpoint of the dispersibility of the component (b), polyethylene glycol and a fatty acid ester of polyethylene glycol are preferable, and a higher fatty acid (carbon number 12 or more) ester of polyethylene glycol or a derivative thereof is more preferable. The addition amount of these polyhydric alcohols and / or ester derivatives thereof is usually 0.1 to 1.0 parts by mass, more preferably 0.1 to 0.8 parts by mass with respect to 100 parts by mass of (a) polyamide. It is. The amount of the higher fatty acid metal salt added is preferably 0.1 parts by mass or more from the viewpoint of tensile elongation and 1.0 part by mass or less from the viewpoint of flame retardancy.

Suitable higher fatty acid esters of polyethylene glycol include polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooleate, especially polyoxyethylene monolaurate, Polyoxyethylene monostearate and polyoxyethylene monooleate are preferred.
Suitable polyethylene glycol higher fatty acid ester derivatives include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan Trioleate is mentioned.

[(D) component: higher fatty acid metal salt]
The higher fatty acid metal salt (d) used in the present invention is a carbon number of capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, serotic acid, montanic acid, mellicic acid, oleic acid, erucic acid, etc. 9 or more higher aliphatic carboxylic acid sodium salts, lithium salts, calcium salts, magnesium salts, zinc salts, aluminum salts and the like. Among these higher fatty acid metal salts, stearic acid metal salts, specifically, Of these, calcium stearate, magnesium stearate, zinc stearate, and aluminum stearate are particularly preferred because they do not reduce the flame retardancy of the finally obtained polyamide resin composition. Furthermore, calcium stearate and aluminum stearate are the most preferable from the viewpoint of less gas generation during molding. The addition amount of these higher fatty acid metal salts is usually 0.01 to 5 parts by mass, particularly preferably 0.05 to 2.0 parts by mass with respect to 100 parts by mass of (a) polyamide. The amount added is preferably 0.01 parts by mass or more from the viewpoint of plasticization during molding, and 5 parts by mass or less from the viewpoint of gas generation and flame retardancy during molding. These higher fatty acid metal salts may be used alone or in combination of two or more.

  The resin composition of this embodiment is a resin composition capable of improving toughness and flame retardancy and reducing toughness variation. The present inventors presume that these characteristics are due to a synergistic effect of the molecular weight component of the polyamide and the dispersibility of the melamine cyanurate. That is, the low molecular weight region (molecular weight 15,000 or less) of the component (a) polyamide is flame retardant and molding stability (mainly at low injection pressure), and the high molecular weight region (molecular weight 100,000 or more) is toughness. It is presumed that these characteristics can be expressed at a high level by expressing the effect and further improving the dispersibility of melamine cyanurate.

[Other ingredients]
The polyamide resin composition of the present invention includes various conventionally used elastomers and fillers, for example, inorganic fibers such as glass fibers and carbon fibers, mica and talc, as long as the purpose of the present invention is not impaired. , Clay minerals, inorganic fillers such as alumina, silica, and apatite, aluminum hydroxide, magnesium hydroxide, zinc borate, zinc stannate, zinc hydroxystannate, ammonium polyphosphate, succinoguanamine, melamine polyphosphate, sulfuric acid Flame retardants such as melamine, melamine phthalate, and aluminum phosphate, pigments and colorants such as titanium white and carbon black, metal phosphites such as sodium hypophosphite, hindered phenols, hindered amines, trialkyl phosphates Thermal stabilizers typified by esters and phosphites, high Fatty acid metal salts, higher fatty acid amides, lubricants such as higher fatty acid esters, various plasticizers, and can be added various additives such as antistatic agents.

[Production Method of Polyamide Resin Composition]
The production method of the polyamide resin composition of the present invention is not particularly limited, and the component (a), the component (b), the component (c), and the component (d) may be melt-kneaded at a time, From the viewpoint of dispersibility of the melamine cyanurate as the component (b), a part of the component (b) may be added after the remaining components are melt-kneaded and further melt-kneaded.

  The shape of the component (a) is not particularly limited, but is preferably a pellet. In this case, from the viewpoint of simplifying the equipment, the component (c) is spread on the pellet surface of the component (a), and then the blend is further spread after the components (b) and (d) are spread. You may knead.

  In the method for producing a polyamide resin composition of the present invention, the method of melt kneading is not particularly limited, but at least one machine is used when mixing the component (a), the component (b), the component (c) and the component (d). It is preferable to use a raw material supply apparatus for supplying to an extruder and melt-kneading. Separate raw material supply devices may be used to supply each component to the extruder, or a single raw material supply device may be used.

  The extruder is not particularly limited, but a twin screw extruder is preferable. Specific examples of the twin screw extruder include the ZSK series manufactured by COPERIION, the TEM series manufactured by Toshiba Machine Co., Ltd., the TEX series manufactured by Nippon Steel Works, Ltd., and the like. / D (screw effective length / screw outer diameter) is preferably in the range of 20 or more and 60 or less, and more preferably 30 or more and 50 or less. In order to make the molecular weight of the polyamide (a) in the resin composition within a specific range, the resin temperature when discharged from the extruder tip nozzle is 25 to 40 ° C. higher than the melting point of the main component polyamide. Preferably, it is controlled by the screw rotation number of the extruder and the number of kneading blocks (referred to as a block in which a plurality of screw elements called kneading disks having a high kneading effect are continuous).

  The method for supplying the raw material to the twin screw extruder is not particularly limited. The raw material supply device is not particularly limited, and a single screw feeder, a twin screw feeder, a table feeder, a rotary feeder, a liquid supply pump, or the like can be used. Of these, the loss-in-weight screw feeder is preferable because it has less fluctuation error in raw material supply. In addition, when a plurality of types of raw materials are input to one raw material supply apparatus, at least two types of raw materials to be input may be mixed after being mixed with a mixer, a cone blender, or the like.

[Molded body]
Since the molded body formed by molding the polyamide resin composition of the present invention has flame retardancy, toughness, and molding stability, electrical and electronic parts such as sockets, switches, cases and covers, and automotive interior and exterior parts It is suitable as an injection molded body used as an automobile electrical component and the like, and as a pellet which is a molding material of these injection molded bodies.

  The present invention will be described in further detail using examples and comparative examples.

(Material property evaluation method)
First, a method for evaluating the physical properties of raw materials will be described. The physical properties of the raw materials used in the examples and comparative examples were evaluated as follows.

<Sulfuric acid relative viscosity>
The 98% sulfuric acid relative viscosity ηr of polyamide 66 was measured according to JIS K6920.

<Molecular weight>
The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of polyamide 66 was measured by the following GPC.
Equipment: “HLC-8320GPC” manufactured by Tosoh Corporation
Detector: Differential refractometer (RI)
Solvent: hexafluoroisopropanol (HFIP) in which 0.1 mol% of sodium trifluoroacetate was dissolved
Column: Tosoh Co., Ltd., "TSKgel-GMHHR-M" 2 and "G1000HHR" 1 connected in series, based on the obtained elution curve, polymethyl methacrylate (PMMA) Calculated by conversion.

<Medium diameter>
The median diameter of the component (b) melamine cyanurate flame retardant was measured using a laser diffraction particle size distribution analyzer (trade name “SALD-7000”, manufactured by Shimadzu Corporation). A sample dispersed in pure water was used as a measurement sample, and measurement was performed using a flow cell. The particle diameter is plotted on the horizontal axis and the frequency (mass) is plotted on the vertical axis, and the particle diameter at which the cumulative mass becomes 50% when the sum of the cumulative mass of frequencies is 100% is defined as the median diameter (D50). .

(Preparation of each component)
[(A) component: polyamide]
(A-1) Component: Polyamide 66
15 kg of an aqueous solution containing 50% by mass of a monomer mixture containing equimolar amounts of hexamethylenediamine and adipic acid was prepared. Next, the monomer aqueous solution was charged into a 40 L autoclave having a stirring device and having a nozzle extracted at the bottom, and the monomer aqueous solution was sufficiently stirred at 50 ° C. After sufficiently replacing the inside of the autoclave with nitrogen, the temperature inside the autoclave was increased from 50 ° C. to about 270 ° C. while the monomer aqueous solution was stirred, and polymerization was performed. At that time, the pressure in the autoclave was about 1.8 MPa in terms of gauge pressure, but water was discharged from the system as needed so that the pressure did not exceed 1.8 MPa. The polymerization time was adjusted so that the ηr of the polyamide 66 resin was about 2.81.

After the polymerization in the autoclave was completed, the polyamide 66 resin was discharged in a strand form from the lower nozzle, and water-cooling and cutting were performed to obtain a pellet-like polyamide 66 (ηr: 2.81, Mw / Mn: 1.98). .
(A-2): Polymerized in the same manner as the component (a-1), and the polymerization time was adjusted so that ηr was about 2.71 to obtain a pellet-like polyamide 66 (ηr: 2.71, Mw). / Mn: 1.97).
(A-3): Polymerized in the same manner as the component (a-1), and the polymerization time was adjusted so that ηr was about 2.75 to obtain pellet-like polyamide 66 (ηr: 2.75, Mw). / Mn: 1.98).
(A-4): Polymerized in the same manner as in the component (a-1), and the polymerization time was adjusted so that ηr was about 2.61, and pellet-like polyamide 66 was obtained (ηr: 2.61, Mw). / Mn: 1.98).
(A-5): Polyamide 6 SF1013A manufactured by Ube Industries

[(B) component: melamine cyanurate]
(B-1): Melamine cyanurate Middle diameter (D50): 10 μm

[Component (c): Polyhydric alcohol and / or ester derivative thereof]
(C-1): Polyoxyethylene monolaurate Emanon (registered trademark) 1112 (PEM) manufactured by Kao Corporation
(C-2): Polyethylene glycol Sanyo Chemical Co., Ltd. PEG400 (PEG)

[(D) component: higher fatty acid metal salt]
(D-1): Calcium stearate Calcium stearate manufactured by Nippon Oil & Fats Co., Ltd.

[Example 1]
(A-1) Polyamide 66, (b-1) Melamine cyanurate, (c-1) PEM, (d-1) Calcium stearate are mixed, and using a loss-in-weight feeder, a twin screw extruder (Coperion ( Co., Ltd. ZSK-40MC, barrel number: 12) was supplied to the first supply port. Extrusion was performed at a barrel temperature of 270 ° C., a discharge rate of 100 kg / hr, and a screw rotation speed of 250 rpm. The screw of the extruder was provided with two kneading blocks. The first kneading block is located in the fourth barrel of the extruder, and the configuration thereof is R-KD (feeding die: 12 mm) L (length in the screw axial direction of the screw constituting the kneading block) from the upstream side. 3 R-type kneading discs, 2 L-N-KD (non-conveying type: N-type kneading discs) with 24 mm, and L-KD with 12 mm L (reverse feed: L-type kneading discs) Is one. The second kneading block is located in the eighth barrel of the extruder, and the construction is from the upstream side, two R-KDs with L of 12 mm, one N-KD with L of 24 mm, and L of 12 mm. One L-KD. Here, the “kneading block” refers to a block called a kneading disk in which a plurality of screw elements having a high kneading effect are continuous.
Next, the polymer was discharged in the form of a strand from the extruder tip nozzle, and water cooling and cutting were performed to obtain polyamide resin composition pellets.

[Examples 2 to 5, Comparative Example 1]
Except having changed the composition of each component as described in Table 1, it carried out similarly to Example 1, and produced the polyamide resin composition pellet of Examples 2-5 and the comparative example 1. FIG.

[Comparative Examples 2 to 5]
The same procedure as in Example 1 was performed except that the screw rotation speed of the extruder was changed to 200 rpm and the second kneading block (located in the eighth barrel) was changed to the conveying block. In addition, a conveyance block refers to the block which is comprised only with a feed-type screw element and does not have a kneading block.

(Evaluation of polyamide resin composition)
The polyamide resin composition pellets of each example and comparative example were evaluated. Table 1 shows the evaluation items and the results. The evaluation method for each evaluation item was as follows.

<Molecular weight>
Quantification and molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of components having a molecular weight of 15,000 or less and components having a molecular weight of 100,000 or more were measured by the following GPC.
Equipment: “HLC-8320GPC” manufactured by Tosoh Corporation
Detector: Differential refractometer (RI)
Solvent: hexafluoroisopropanol (HFIP) in which 0.1 mol% of sodium trifluoroacetate was dissolved
Column: Tosoh Co., Ltd., "TSKgel-GMHHR-M" 2 and "G1000HHR" 1 connected in series, based on the obtained elution curve, polymethyl methacrylate (PMMA) Calculated by conversion.

<Thin wall tensile test>
Using an injection molding machine (SE50D manufactured by Sumitomo Heavy Industries, Ltd.), the polyamide resin composition pellets are set to a cylinder temperature of 270 ° C. and a mold temperature of 80 ° C., and injection molding conditions are 10 seconds for injection and 10 seconds for cooling. The test piece of 0.5 mm thickness was obtained by injection molding. Using the obtained dumbbell test piece, tensile elongation was measured under conditions of a distance between chucks of 55 mm and a tensile speed of 50 mm / min. At this time, the standard deviation was calculated from the tensile elongation values of 10 test pieces.

<Hinge standard deviation>
The polyamide resin composition pellets were set to a cylinder temperature of 270 ° C. and a mold temperature of 80 ° C. using an injection molding machine (manufactured by Nissei Kogyo Co., Ltd .: PS40E), and the hinge molded body 10 shown in FIG. 1 and FIG. Was molded. FIG. 1 is a top view of the hinge molded body 10, and FIG. 2 is a side view of the hinge molded body 10. The hinge molded body 10 includes a hinge portion 12. About the produced hinge molded object 10 of each example, the hinge part 12 was bent almost 180 degrees using an automatic repeater hinge test machine in 23 degreeC and 50% RH atmosphere, and it was in the original position (0 degree) position. The returning operation was repeated at a rate of 33 times / minute, and the number of bending times at which the material was bent and broken was measured. In the hinge test, 15 pieces were measured, and the standard deviation of 15 pieces was used as an index of variation.

<Molding stability (spiral flow length)>
The polyamide resin composition pellets are set to a cylinder temperature of 270 ° C. and a mold temperature of 80 ° C. using an injection molding machine (SE50D manufactured by Sumitomo Heavy Industries, Ltd.), injection 10 seconds, cooling 10 seconds, injection speed 200 mm. / S and injection pressure of 40 MPa, injection molding was performed using a spiral flow mold having a width of 10 mm and a thickness of 1 mm, and the flow length was measured after 15 discarded shots. Molding stability was determined according to the following criteria by measuring the flow lengths of the first and fifth shots.

(Evaluation criteria)
A: Difference in flow length between 1st shot and 5th shot is less than ± 2mm B: Difference in flow length between 1st shot and 5th shot is ± 2mm or more

<Flame retardance>
The polyamide resin composition pellets were set to 270 ° C. and a mold temperature of 80 ° C. using an injection molding machine (PS40E manufactured by Nissei Resin Co., Ltd.), and a UL-94 vertical combustion test measurement test piece was injection molded ( (Thickness: 0.40 mm, 0.80 mm). Using the five test pieces having different thicknesses formed in this way, flame retardancy was evaluated based on the UL-94 vertical combustion test, and flame retardancy V-0, V-1, V-2, HB The judgment of was carried out.

As shown in Table 1, according to the present invention, it is excellent in flame retardancy and toughness, and toughness variation can also be reduced.
On the other hand, Comparative Examples 1 and 2 in which the proportion of the polyamide component having a molecular weight of 100,000 or more is less than 4.0% by mass have good hinge characteristics but poor tensile elongation and large variation. Further, Comparative Examples 3 to 5 in which the proportion of the polyamide component having a molecular weight of 15,000 or less is less than 15% by mass have good hinge characteristics and tensile elongation, but have large variations in tensile elongation, flame retardancy, and molding stability. Inferior to

  Since the polyamide resin composition of the present invention has high flame retardancy, it is useful as an industrial material for various machine industry parts and electrical / electronic parts, particularly connectors and clips.

10 Hinge molded body 12 Hinge

Claims (11)

A resin composition comprising (a) polyamide and (b) melamine cyanurate,
The proportion of the component having a molecular weight of 15,000 or less obtained from gel permeation chromatography (GPC) in the (a) polyamide is 15.0 to 30.0 mass% of the whole (a) polyamide, and the molecular weight The polyamide resin composition whose ratio of 100,000 or more component is 4.0-8.0 mass% of the whole (a) polyamide.   2. The polyamide resin composition according to claim 1, wherein (a) the polyamide has a molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of 1.90 to 2.00.   The polyamide resin composition according to claim 1 or 2, further comprising (c) a polyhydric alcohol and / or an ester derivative thereof.   The polyamide resin composition according to any one of claims 1 to 3, further comprising (d) a higher fatty acid metal salt.   The polyamide resin composition according to any one of claims 1 to 4, comprising 2 to 20 parts by mass of the (b) melamine cyanurate with respect to 100 parts by mass of the (a) polyamide.   100 parts by mass of the (a) polyamide, 2-20 parts by mass of the (b) melamine cyanurate, 0.1-1.0 parts by mass of the (c) polyhydric alcohol and / or ester derivative thereof, and / or Or the polyamide resin composition of Claim 3 or 4 which contains 0.05-2.0 mass parts of said (d) higher fatty acid metal salt.   The polyamide resin composition according to any one of claims 1 to 6, wherein 80% by mass or more of the polyamide (a) is polyamide 66.   The polyamide resin composition according to any one of claims 1 to 6, wherein the polyamide (a) is polyamide 66.   The polyamide resin composition according to claim 7 or 8, wherein the (a) polyamide 66 has a sulfuric acid relative viscosity ηr of 2.65 to 2.88.   The polyamide resin composition according to claim 7 or 8, wherein the (a) polyamide 66 has a sulfuric acid relative viscosity ηr of 2.73 to 2.88.   The molded object formed by shape | molding the polyamide resin composition of any one of Claims 1-10.