JP6867782B2 - Polyamide resin composition and its molded product - Google Patents

Description

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

Polyamide resins have been widely used in various parts such as automobile parts, electronic and electrical parts, and industrial machine parts because they have excellent properties such as molding processability as well as machine properties. It is used in products with hinges such as connectors and clips because of its excellent toughness. In many cases, these products are required to be flame-retardant. In particular, it is desired to use a non-halogen flame retardant from an environmental point of view.

A typical example of such a flame-retardant polyamide resin is a flame-retardant polyamide material using melamine cyanurate, which is used, for example, in connectors and clips in the 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-A-53-125459 Japanese Unexamined Patent Publication No. 53-031759 JP-A-11-106645

In the flame-retardant polyamide resin using melamine cyanurate, melamine cyanurate is not sufficiently compatible with the polyamide resin and is filled in the composition in a dispersed form like an inorganic filler. Therefore, the toughness of the polyamide resin composition filled with melamine cyanurate tends to decrease.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polyamide resin composition having improved flame retardancy and toughness and reduced toughness variation.

As a result of diligent studies to solve the above problems, the present inventor has improved flame retardancy and toughness by setting the molecular weight component amount of polyamide in the resin composition containing polyamide and melamine cyanurate within a specific range. We 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 containing (a) polyamide and (b) melamine cyanurate, wherein the proportion of components having a molecular weight of 15,000 or less determined by gel permeation chromatography (GPC) in (a) polyamide is determined. (A) 15.0 to 30.0% by mass of the total polyamide, and the proportion of components having a molecular weight of 100,000 or more is (a) 4.0 to 8.0% by mass of the total polyamide.

(A) The molecular weight distribution of the polyamide (weight average molecular weight (Mw) / number average molecular weight (Mn)) 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.

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

It is preferable that (a) polyamide is contained in an amount of 100 parts by mass and (b) melamine cyanurate is contained in an amount of 2 to 20 parts by mass.

The polyamide resin composition of the present invention contains (a) 100 parts by mass of polyamide, (b) 2 to 20 parts by mass of melamine cyanurate, and (c) a polyhydric alcohol and / or an ester derivative thereof. It preferably contains 0 parts by mass.

Further, it is preferable that (a) polyamide is contained in an amount of 100 parts by mass, (b) melamine cyanurate is contained in an amount of 2 to 20 parts by mass, and (d) a higher fatty acid metal salt is contained in an amount of 0.05 to 2.0 parts by mass.

Further, (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 an ester derivative thereof, and (d). ) It is preferable to contain 0.05 to 2.0 parts by mass of the higher fatty acid metal salt.

It is preferable that 80% by mass or more of the polyamide (a) is the polyamide 66.

The polyamide (a) is more preferably polyamide 66.

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

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

The molded product 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 containing (a) polyamide and (b) melamine cyanurate, and has a molecular weight determined by gel permeation chromatography (GPC) in (a) polyamide resin. The proportion of the component of 15,000 or less is (a) 15.0 to 30.0% by mass of the whole polyamide, and the proportion of the component having a molecular weight of 100,000 or more is (a) 4.0 of the whole polyamide. Since it is ~ 8.0% by mass, the flame retardancy and toughness are improved without impairing 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 has a molecular weight determined by gel permeation chromatography (GPC) in (a) polyamide resin. The proportion of the component of 15,000 or less is (a) 15.0 to 30.0% by mass of the whole polyamide, and the proportion of the component having a molecular weight of 100,000 or more is (a) 4.0 of the whole polyamide. ~ 8.0% by 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, and is, for example, polycaprolactam (polyamide 6), polytetramethylene adipamide (polyamide 46), or polyhexamethylene. Adipamide (polyamide 66), polyhexamethylenecyclohexylamide (polyamide 6C), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polyundecalactum (polyamide 11), polydodeca Lactum (polyamide 12), polyhexamethylene isophthalamide (polyamide 6I), polyhexamethylene terephthalamide (polyamide 6T), polynonane methylene terephthalamide (polyamide 9T), polydodecamethylene terephthalamide (polyamide 12T), polymethoxylylenazi Examples thereof include a polyamide (polyamide MXD6) and a polyamide copolymer containing at least two different polyamide-forming components thereof, and a mixture thereof.

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

<Molecular weight of polyamide in the composition>
The polyamide used in the polyamide resin composition of the present invention reduces the variation in flame retardancy, toughness, and toughness by setting a specific amount of each of a component having a molecular weight of 15,000 or less and a component having a molecular weight of 100,000 or more. be able to. Specifically, from the viewpoint of flame retardancy and molding stability, 15.0 to 30.0% by mass of components having a molecular weight of 15,000 or less is 15.0 to 30.0% by mass with respect to the entire polyamide, and 15.0 to 20.0% by mass. % Is more preferable. Further, from the viewpoint of flame retardancy and toughness, the content having a molecular weight of 100,000 or more is 4.0 to 8.0% by mass, 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 toughness variation and molding stability.
In order to set the molecular weight of polyamide in the polyamide resin composition to a specific amount, it is preferable to control the screw rotation speed and screw configuration at the time of melt-kneading of the extruder, for example.

The molecular weight of the polyamide is obtained by measurement using gel permeation chromatography (GPC). The device is "HLC-8320GPC" manufactured by Tosoh Corporation, the detector is a differential refractometer (RI), and the solvent is hexafluoroisopropanol (HFIP) in which 0.1 mol% of sodium trifluoroacetate is dissolved. Used two "TSKgel-GMHHR-M" and one "G1000HHR" manufactured by Tosoh Corporation. The sample concentration was 1 to 3 (mg sample) / 1 (mL solvent), and the sample was used as a measurement sample by filtering with a filter to remove insoluble matter. Based on the obtained elution curve, it was calculated by polymethyl methacrylate (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, and 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., an aqueous solution of melamine and an aqueous solution of cyanuric acid are stirred and mixed for reaction. It is obtained by precipitating and filtering the product thus obtained. The obtained product is a white solid, and it is preferable to pulverize it into a fine powder before use.

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

The median diameter (D50) of (b) melamine cyanurate before being mixed with the polyamide component (a) is not particularly limited, but is preferably 1 μm to 20 μm from the viewpoint of dispersibility of melamine cyanurate. More preferably, 1.5 μm to 15 μm. 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. Since 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, the medium diameter (D50) is defined in JIS Z8901 when the mass of particles larger than a certain particle size occupies 50% of the mass of the whole particle in the particle size distribution of the particles. It is a particle size and can be measured by, for example, a laser diffraction / scattering method. Specifically, by the laser diffraction / scattering method, the particle size is plotted on the horizontal axis and the frequency (mass) is plotted on the vertical axis, and the cumulative mass is 50% when the total cumulative mass of this frequency is 100%. It can be measured as a particle size.

The blending amount of melamine cyanurate is 2 to 20 parts by mass, preferably 3 to 15 parts by mass with respect to 100 parts by weight of the polyamide. 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 the blending of melamine cyanurate into the polyamide resin, but industrially, a method of kneading and blending with an extruder or the like is preferable.

[Component (c): polyhydric alcohol and / or ester derivative thereof]
The polyhydric alcohol and / or its ester derivative used in the present invention preferably contains at least one polyalkylene polyhydric alcohol and its fatty acid ester. Glycos 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, pentaerythlit, etc. Examples of the polyhydric alcohol and the fatty acid ester of the polyalkylene polyhydric alcohol include polyalkylene polyhydric alcohols such as polyethylene glycol, polypropylene glycol and polybutylene glycol, and capric acid, lauric acid, myristic acid, palmitic acid and stear. Examples thereof include esters or derivatives thereof with aliphatic carboxylic acids such as acids, behenic acid, cellotic acid, montanic acid, melic acid, oleic acid, and erucic acid, which are easily available industrially. (B) From the viewpoint of component dispersibility, polyethylene glycol and polyethylene glycol fatty acid esters are preferable, and polyethylene glycol higher fatty acid (12 or more carbon atoms) esters or derivatives thereof are more preferable. The amount of these polyhydric alcohols and / or ester derivatives added 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. Is. The amount of the higher fatty acid metal salt added is preferably 0.1 part 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, and in particular polyoxyethylene monolaurate, Polyoxyethylene monostearate and polyoxyethylene monooleate are preferable.
Suitable higher fatty acid ester derivatives of polyethylene glycol include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, and polyoxyethylene sorbitan. Trioleate can be mentioned.

[Component (d): higher fatty acid metal salt]
The higher fatty acid metal salt (d) used in the present invention has the number of carbon atoms of capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, cellotic acid, montanic acid, melisic acid, oleic acid, erucic acid and the like. 9 or more higher aliphatic carboxylic acid sodium salts, lithium salts, calcium salts, magnesium salts, zinc salts, aluminum salts and the like can be mentioned. Among these higher fatty acid metal salts, stearic acid metal salts, specifically Is particularly preferable because calcium stearate, magnesium stearate, zinc stearate, and aluminum stearate do not reduce the flame retardancy of the finally obtained polyamide resin composition. Further, calcium stearate and aluminum stearate are most preferable because they generate less gas during molding. The amount of these higher fatty acid metal salts added 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 part 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. Further, these higher fatty acid metal salts may be used alone or in combination of two or more.

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

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

[Manufacturing method of polyamide resin composition]
The method for producing the polyamide resin composition of the present invention is not particularly limited, and the components (a), (b), (c), and (d) may be melt-kneaded at once. From the viewpoint of the dispersibility of the melamine cyanurate of the component (b), a part of the component (b) may be added after melt-kneading all the remaining components and further melt-kneaded.

The shape of the component (a) is not particularly limited, but it is preferably in the form of pellets. 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 component (b) and the component (d) are spread and then melted. You may knead.

In the method for producing the 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 components (a), (b), (c) and (d). A method of supplying to an extruder using the raw material supply device of the above and melt-kneading is preferable. A separate raw material supply device may be used for supplying each component to the extruder, or one 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 COPERION, the TEM series manufactured by Toshiba Machine Co., Ltd., and the TEX series manufactured by Japan Steel Works, Ltd. / D (effective screw length / outer diameter of screw) is preferably in the range of 20 or more and 60 or less, and preferably 30 or more and 50 or less. In order to set the molecular weight of (a) polyamide in the resin composition within a specific range, extrusion is performed under the condition that the resin temperature at the time of ejection from the extruder tip nozzle is 25 to 40 ° C. higher than the melting point of the main component polyamide. This is preferably performed, and can be controlled by the screw rotation speed of the extruder and the number of kneading blocks (referring to a block in which a plurality of screw elements having a high kneading effect called a kneading disc are continuous).

The method of 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 screw feeder, a table feeder, a rotary feeder, a liquid supply pump, or the like can be used. Of these, the loss-in weight type screw feeder is preferable because it has less fluctuation error in the supply of raw materials. Further, when a plurality of types of raw materials are charged into one raw material supply device, at least two types of raw materials may be mixed with a mixer, a corn blender, or the like before charging.

[Molded product]
Since the molded product obtained 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 automobile interior / exterior parts. It is suitable as an injection molded product used as an automobile electrical component or the like, and as a pellet which is a molding material for these injection molded products.

The present invention will be described in more detail with reference to Examples and Comparative Examples.

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

<Relative viscosity of sulfuric acid>
The 98% sulfuric acid relative viscosity ηr of the 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 the 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 is dissolved.
Column: Using two "TSKgel-GMHHR-M" and one "G1000HHR" manufactured by Tosoh Corporation in series, based on the elution curve obtained, polymethyl methacrylate (PMMA) Calculated by conversion.

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

(Preparation of each ingredient)
[(A) component: polyamide]
(A-1) Component: Polyamide 66
An aqueous solution containing 50% by mass of a monomer mixture containing equimolar amounts of hexamethylenediamine and adipic acid was prepared. Next, the above-mentioned monomer aqueous solution was charged into a 40 L-volume autoclave having a stirring device and a extraction nozzle 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 raised from 50 ° C. to about 270 ° C. while stirring the monomer aqueous solution for polymerization. At that time, the pressure in the autoclave was about 1.8 MPa in gauge pressure, but water was discharged to the outside of the system at any time 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 from the lower nozzle in a strand shape, and after water cooling and cutting, a pellet-shaped polyamide 66 was obtained (ηr: 2.81, Mw / Mn: 1.98). ..
(A-2): Polymerization was carried out in the same manner as the component (a-1), and the polymerization time was adjusted so that ηr was about 2.71 to obtain pellet-shaped polyamide 66 (ηr: 2.71, Mw). / Mn: 1.97).
(A-3): Polymerization was carried out 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-shaped polyamide 66 (ηr: 2.75, Mw). / Mn: 1.98).
(A-4): Polymerization was carried out in the same manner as the component (a-1), and the polymerization time was adjusted so that ηr was about 2.61 to obtain pellet-shaped polyamide 66 (ηr: 2.61, Mw). / Mn: 1.98).
(A-5): Polyamide 6 Ube Industries SF1013A

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

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

[Component (d): higher fatty acid metal salt]
(D-1): Calcium stearate Calcium stearate manufactured by NOF CORPORATION

[Example 1]
(A-1) Polyamide 66, (b-1) Melamine cyanurate, (c-1) PEM, (d-1) Calcium stearate are mixed, and a twin-screw extruder (Coperion (Coperion) ZSK-40MC manufactured by Co., Ltd., number of barrels: 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 its configuration is R-KD (feed type: feed type: L) (length in the screw axial direction of the screws constituting the kneading block) of 12 mm from the upstream side. 3 R-type kneading discs), 2 N-KDs with 24 mm L (non-conveying type: N-type kneading discs), 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 its configuration is two R-KDs with an L of 12 mm, one N-KD with an L of 24 mm, and an L of 12 mm from the upstream side. One L-KD of. The term "kneading block" as used herein refers to a block called a kneading disc in which a plurality of screw elements having a high kneading effect are continuous.
Next, the polymer was discharged in a strand shape from the tip nozzle of the extruder, and water-cooled and cut to obtain a polyamide resin composition pellet.

[Examples 2 to 5, Comparative Example 1]
Polyamide resin composition pellets of Examples 2 to 5 and Comparative Example 1 were prepared in the same manner as in Example 1 except that the composition of each component was as shown in Table 1.

[Comparative Examples 2 to 5]
The same procedure as in Example 1 was carried out except that the screw rotation speed of the extruder was 200 rpm and the second kneading block (located in the eighth barrel) was changed to a transfer block. The transport block refers to a block that is composed only of 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 each evaluation item and its result. The evaluation method for each evaluation item is as follows.

<Molecular weight>
The quantification and molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the components having a molecular weight of 15,000 or less and the 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 is dissolved.
Column: Using two "TSKgel-GMHHR-M" and one "G1000HHR" manufactured by Tosoh Corporation in series, based on the elution curve obtained, polymethyl methacrylate (PMMA) Calculated by conversion.

<Thin wall tensile test>
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 (SE50D manufactured by Sumitomo Heavy Industries, Ltd.), and injection molding conditions of 10 seconds for injection and 10 seconds for cooling. A test piece having a thickness of 0.5 mm was obtained by injection molding. Using the obtained dumbbell test piece, the tensile elongation was measured under the 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 values of tensile elongation of 10 test pieces.

<Hinge standard deviation>
The polyamide resin composition pellet was 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 FIGS. 1 and 2 was set. 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. For the hinge molded body 10 of each of the produced examples, the hinge portion 12 was bent to almost 180 ° using an automatic repeating hinge tester at 23 ° C. and a 50% RH atmosphere, and returned to the original position (0 °). The returning operation was repeated at a speed of 33 times / minute, and the number of bending steps to break and break was measured. In the hinge test, 15 lines were measured, and the standard deviation of 15 lines was used as an index of variation.

<Molding stability (spiral flow length)>
The polyamide resin composition pellet was 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.), and injection 10 seconds, cooling 10 seconds, injection speed 200 mm. Injection molding was performed under the conditions of / s and an injection pressure of 40 MPa, molded with a spiral flow mold having a width of 10 mm and a thickness of 1 mm, and the flow length was measured after 15 discard shots. The molding stability was determined by measuring the flow lengths of the first shot and the fifth shot and using the following criteria.

(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 retardant>
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 test piece for UL-94 vertical combustion test measurement was injection molded ( Thickness: 0.40 mm, 0.80 mm). Flame retardancy was evaluated based on the UL-94 vertical combustion test using five test pieces of different thicknesses thus formed, and flame retardancy V-0, V-1, V-2, HB. Was determined.

表１に示すように、本発明によれば、難燃性や靱性に優れるとともに、靱性のバラつきも低減することができる。
一方、分子量が１００，０００以上のポリアミド成分の割合が４．０質量％未満である比較例１および２は、ヒンジ特性は良いが、引張伸びが劣り、ばらつきも大きい。また、分子量が１５，０００以下のポリアミド成分の割合が１５質量％未満である比較例３〜５は、ヒンジ特性および引張伸びは良いが、引張伸びのばらつきが大きく、難燃性および成形安定性に劣る。

As shown in Table 1, according to the present invention, not only excellent flame retardancy and toughness, but also variation in toughness can 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, in 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, the hinge characteristics and the tensile elongation are good, but the tensile elongation varies widely, and the flame retardancy and molding stability are large. Inferior to.

Since the polyamide resin composition of the present invention has high flame retardancy, it is useful as various mechanical and electronic parts, particularly industrial materials such as connectors and clips.

10 Hinge molded body 12 Hinge

Claims (12)

A resin composition containing (a) polyamide and (b) melamine cyanurate.
The proportion of the component having a molecular weight of 15,000 or less determined by gel permeation chromatography (GPC) in the (a) polyamide is 15.0 to 30.0% by mass and the molecular weight of the entire (a) polyamide. A polyamide resin composition in which the proportion of 100,000 or more components is 4.0 to 8.0% by mass of the total polyamide (a). The polyamide resin composition according to claim 1, wherein the (a) polyamide molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) is 1.90 to 2.00. (C) The polyamide resin composition according to claim 1 or 2, further comprising a polyhydric alcohol and / or an ester derivative thereof. With respect to 100 parts by mass of the (a) polyamide, the (c) polyhydric alcohol and / or The polyamide resin composition according to claim 3, which contains 0.1 to 1.0 parts by mass of the ester derivative. .. (D) The polyami according to any one of claims 1 to 4, further comprising a higher fatty acid metal salt. Resin composition. The polyamide resin composition according to claim 5, wherein (a) the polyamide is 100 parts by mass and 0.05 to 2.0 parts by mass of the (d) higher fatty acid metal salt is contained. 2 to 100 parts by mass of the (a) polyamide and 2 to 2 of the (b) melamine cyanurate. The polyamide resin composition according to any one of claims 1 to 6, which contains 20 parts by mass. The polyamide resin composition according to any one of claims 1 to 7 , 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 7 , wherein the polyamide (a) is a polyamide 66. The polyamide resin composition according to claim 8 or 9, wherein the (a) polyamide 66 has a relative sulfuric acid viscosity ηr of 2.65 to 2.88. The polyamide resin composition according to claim 8 or 9, wherein the (a) polyamide 66 has a relative sulfuric acid viscosity ηr of 2.73 to 2.88. A molded product obtained by molding the polyamide resin composition according to any one of claims 1 to 11.

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