JP6800652B2 - Polyamide resin composition and its molded product - Google Patents

Description

The present invention relates to a polyamide resin composition, and more particularly to a polyamide resin composition having excellent flame retardancy and hinge characteristics and a molded product thereof.

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 mechanical properties. It is used for 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 Documents 3 and 4 propose a method in which a masterbatch having a high concentration of melamine cyanurate is prepared in advance and mixed with a polyamide resin by a molding machine or the like for molding. Further, Patent Document 5 proposes that a specific dispersant is blended at the stage of mixing the polyamide resin and melamine cyanurate.

JP-A-53-125459 Japanese Unexamined Patent Publication No. 53-031759 Japanese Unexamined Patent Publication No. 08-245875 Japanese Unexamined Patent Publication No. 11-302533 Japanese Unexamined Patent Publication No. 2003-301104

In the flame-retardant polyamide resin using melamine cyanurate, melamine cyanurate is not sufficiently compatible with the polyamide resin and is packed 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. Conventional techniques such as making a masterbatch or dispersing with a dispersant cannot achieve a balance between flame retardancy, which is a contradictory performance, and hinge characteristics.
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 which is excellent not only in flame retardancy and hinge characteristics but also in improved variation in hinge characteristics.

As a result of diligent studies to solve the above problems, the present inventor has set the resin composition containing the polyamide resin and melamine cyanurate in a specific range, and the 98% sulfuric acid relative viscosity ηr of the polyamide resin composition in the polyamide resin composition. By setting the average particle size of melamine cyanurate in the above range within a predetermined range, it has been found that excellent flame retardancy and hinge characteristics are provided, and the present invention has been completed.

That is, the polyamide resin composition of the present invention is
A polyamide resin composition containing (A) a polyamide 66/6 copolymer, (B) a polyamide 6 resin, and (C) a melamine cyanurate-based flame retardant, wherein the total of the components (A) and (B) is 100 mass. The part (C) contains 4 to 8 parts by mass of the flame retardant, and the polyamide 66/6 copolymer of the component (A) contains 66 units of polyamide 50 to 95% by mass and 6 units of polyamide 5 to 50% by mass. % consists polyamide resin composition of the polyamide 66 units / polyamide 6 units of weight ratio 88 / 12-73 / 27, 98% sulfuric acid relative viscosity of the polyamide resin composition ηr (JIS K6920 compliant) is 2.50～ 2.83, The average particle size of the component (C) in the polyamide resin composition is 1.0 μm or less.

A surfactant containing at least one polyalkylene polyhydric alcohol fatty acid ester is further contained in an amount of 0.1 to 1.0 parts by mass based on 100 parts by mass of the total of the components (A) and (B). Is preferable.
The component (A) preferably has a 98% sulfuric acid relative viscosity ηr (based on JIS K6920) of 2.3 to 2.9.
The component (B) preferably has a 98% sulfuric acid relative viscosity ηr (based on JIS K6920) of 2.1 to 2.7.
The 98% sulfuric acid relative viscosity ηr (JIS K6920 compliant) of the polyamide resin composition is more preferably 2.50 to 2.70.

The component (D) is polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, It is preferably at least one selected from the group consisting of polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan trioleate.

The molded product of the present invention is formed by molding the polyamide resin composition of the present invention.
The molded body may be a connector component having a hinge portion.
The molded body may be a clip.

The polyamide resin composition of the present invention is a polyamide resin composition containing (A) a polyamide 66/6 copolymer, (B) a polyamide 6 resin, and (C) a melamine cyanurate-based flame retardant, and is a component (A). And 4 to 8 parts by mass of the component (C) with respect to a total of 100 parts by mass of the component (B), and the polyamide 66/6 copolymer of the component (A) has 66 units of polyamide 50 to 95% by mass. It consists of 6 units of polyamide from 5 to 50% by mass, the mass ratio of 66 units of polyamide / 6 units of polyamide in the polyamide resin composition is 88/12 to 73/27, and the 98% sulfuric acid relative viscosity ηr (JIS K6920) of the polyamide resin composition. (Compliant) is 2.50 to 2.83, and the average particle size of the component (C) in the polyamide resin composition is 1.0 μm or less. Therefore, the mechanical properties, chemical resistance, and goodness inherent in the polyamide resin composition are good. It is possible to improve flame retardancy and hinge characteristics without impairing moldability, electrical characteristics, etc., and it can be suitably used for applications such as home appliance parts, electronic parts, and automobile parts.

It is a top view of the molded product used for the test of the hinge characteristic. It is a side view of the molded product used for the test of a hinge characteristic.

Hereinafter, the present invention will be described in detail.
[Polyamide resin composition]
The polyamide resin composition of the present invention is a polyamide resin composition containing (A) a polyamide 66/6 copolymer and / or a polyamide 66 resin, (B) a polyamide 6 resin, and (C) a melamine cyanurate flame retardant. The mass ratio of 66 units of polyamide / 6 units of polyamide in the polyamide resin composition contains 4 to 8 parts by mass of component (C) with respect to 100 parts by mass of the total of component (A) and component (B). 88/12 to 73/27, 98% sulfuric acid relative viscosity ηr (JIS K6920 compliant) of the polyamide resin composition is 2.50 to 2.83, and the average particle size of the component (C) in the polyamide resin composition is 1. It is 0 μm or less.
Hereinafter, each component will be described in detail.

[Component (A): Polyamide 66/6 copolymer and / or Polyamide 66 resin]
The polyamide 66 resin is a polymer having an amide bond (-NHCO-) in the main chain and composed of hexamethylene units and adipic acid units. The polyamide 66 resin is not particularly limited, but for example, a polymer obtained by polycondensing hexamethylenediamine and adipic acid, a polymer obtained by polycondensing 6-aminocapronitrile and adipic acid, and the like. Examples thereof include a polymer obtained by polycondensing hexamethylenediamine and adipoyl chloride, and a polymer obtained by polycondensing 6-aminocapronitrile and adipoyl chloride. Of these, a polymer obtained by polycondensing hexamethylenediamine and adipic acid is preferable because of the availability of raw materials.

The polyamide 66/6 copolymer is a copolymer of 66 units of polyamide and 6 units of polyamide, and preferably, the polyamide 66 is composed of 50 to 95% by mass of 66 units of polyamide and 5 to 50% by mass of 6 units of polyamide. It is a / 6 copolymer, more preferably a polyamide 66/6 copolymer composed of 80 to 90% by mass of 66 units of polyamide and 10 to 20% by mass of 6 units of polyamide.
By using such a polyamide resin, the flame retardancy and hinge characteristics of the polyamide resin composition of the present invention can be further improved. It is also preferable from the viewpoint of compatibility with the polyamide 6 resin (B) described later.

The relative viscosity of the component (A) measured at a concentration of 1% in 98% sulfuric acid and 25 ° C. according to JIS K6920 is preferably in the range of 2.3 to 2.9, and is preferably in the range of 2.3 to 2.8. More preferred. By setting the relative viscosity of the component (A) to 2.3 or more, the toughness and mechanical strength of the molded product can be further improved. Further, by setting the relative viscosity to 2.9 or less, flame retardancy and molding processing of the molded product can be further facilitated, and the appearance can be improved.

As the component (A), a copper compound containing copper acetate or copper iodide (potassium iodide may be used in combination) may be added, or a hindered phenol-based heat stabilizer or a hindered amine-based heat stabilizer may be added. It is preferable to prepare a heat-stabilizing formulation by containing an organic heat stabilizer such as a phosphorus-based heat stabilizer. Thereby, the thermal stability of the polyamide resin composition of the present invention can be further improved.

The above heat-stabilizing formulation may be carried out in any manufacturing process. For example, copper acetate, copper iodide and an organic heat stabilizer may be added to the monomer and then polymerized, or after the polymer is obtained by polymerization, in a processing process using an extruder, a molding machine or the like. It may be added to the melted polyamide resin. Further, it may be directly mixed with the polymer pellets and then subjected to a molding process.

[Component (B): Polyamide 6 resin]
The (B) polyamide 6 resin contained in the polyamide resin composition of the present invention is necessary for exhibiting the high hinge characteristics of the polyamide resin composition. The amount of the component (B) is not particularly limited, but the mass ratio of 66 units of polyamide / 6 units of polyamide in the polyamide resin composition is from 88/12 to 88/12 from the viewpoint of suppressing variation in hinge characteristics and hinge characteristics and mechanical properties. It is 73/27, preferably 88/12 to 75/25, and more preferably 86/14 to 75/25. By setting the mass ratio of the polyamide 6 to 12 or more, the hinge characteristics can be further improved, and by setting it to 27 or less, the compatibility with the component (A) can be made sufficient, and the hinge characteristics can be improved. It is possible to improve the effect of suppressing the variation of.

The relative viscosity of the component (B) measured at a concentration of 1% in 98% sulfuric acid and 25 ° C. according to JIS K6920 is preferably in the range of 2.1 to 2.7, and preferably in the range of 2.4 to 2.6. More preferred. By setting the relative viscosity of the component (B) to 2.1 or more, the hinge characteristics, toughness, mechanical strength, and flame retardancy of the molded product can be further improved. By setting the relative viscosity to 2.7 or less, the flame retardancy of the molded product can be further improved and the appearance can be improved.

[(C) component: melamine cyanurate flame retardant]
The component (C) contained in the polyamide resin composition of the present invention is a reaction product of melamine or a derivative thereof and cyanuric acid or a derivative thereof, and is not particularly limited as long as it is such a reaction product. As the component (C), for example, melamine or a derivative thereof is added to an aqueous solution of cyanuric acid or a derivative thereof, and the mixture is stirred at about 90 to 100 ° C., and the precipitate obtained as a reaction product is filtered and dried. It can be produced by crushing it into a fine powder.

Preferred (C) components include melamine cyanurate, which is an equimolar reaction product of melamine and cyanuric acid. 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 in the present invention, industrially available commercially available melamine cyanurates can be appropriately used.

The component (C) exhibits a dispersed state dispersed in the component (A) and the component (B). Therefore, the average particle size of the component (C) in the polyamide resin composition can be observed by observing the cross section of the resin composition using a scanning electron microscope (SEM). More specifically, the polyamide resin composition is cut and the cut surface is observed using a scanning electron microscope (SEM). When the observation target is a columnar pellet shape, the observation direction is cut into a cross section substantially perpendicular to the long side of the pellet and observed. If it is a molded piece, observe it in a cross section perpendicular to the flow direction. When the particle of the component (C) is not spherical, the diameter passing through the center of gravity of the particle is measured in 2 ° increments, and the average value is taken as the particle size of the particle. The average particle size is an average value of dispersed particles measured by an image analysis device (image analysis software).

The average particle size of the component (C) in the polyamide resin composition is 1.0 μm or less. By setting the average particle size of the component (C) in the polyamide resin composition to 1.0 μm or less, the tensile elongation, hinge characteristics, low temperature hinge, etc. of the resin composition can be improved.
The average particle size of the component (C) in the polyamide resin composition may be any method as long as it can be controlled to 1.0 μm or less, but it is melt-kneaded together with the components (A) and (B) and pulverized by mechanical shearing. The method is preferable from the economical point of view.

The median diameter (D50) of the component (C) before being mixed with the component (A) and the component (B) is not particularly limited, but may be 1 μm to 5 μm from the viewpoint of the dispersibility of the component (C). It is preferably 1.5 μm to 4 μm, more preferably. When the median diameter of the component (C) is 1 μm or more, handling becomes easy and deterioration of the cohesiveness of the component (C) can be suppressed. Since the median diameter of the component (C) is 5 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 is measured by 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 is 50% when the total cumulative mass of this frequency is 100%. It is a value measured as a particle size.

The content of the component (C) in the polyamide resin composition is 4 to 8 parts by mass with respect to 100 parts by mass in total of the components (A) and (B) from the viewpoint of flame retardancy and toughness. ~ 7 parts by mass is preferable, 4 to 6 parts by mass is more preferable, and 4 to 5.5 parts by mass is particularly preferable.

[Component (D): Surfactant]
The polyamide resin composition of the present invention preferably contains a surfactant containing a fatty acid ester of at least one polyalkylene polyhydric alcohol.
Examples of the fatty acid ester of the polyalkylene polyvalent alcohol include polyalkylene polyvalent alcohols such as polyethylene glycol, polypropylene glycol and polybutylene glycol, and capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid and cellotin. Examples thereof include esters or derivatives thereof with aliphatic carboxylic acids such as acids, montanic acid, melissic acid, oleic acid, and erucic acid, which are easily available industrially. From the viewpoint of the dispersibility of the component (C), a fatty acid ester of polyethylene glycol is preferable, and a higher fatty acid (12 or more carbon atoms) ester of polyethylene glycol or a derivative thereof is more preferable.

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 is mentioned.

The content of the component (D) in the polyamide resin composition is preferably 0.1 to 1.0 parts by mass with respect to 100 parts by mass in total of the components (A) and (B). With such a content, the component (C) is well dispersed in the polyamide resin composition, and the polyamide resin composition having further improved hinge characteristics and flame retardancy can be obtained. Further, it has been confirmed that by setting the component (C) and the component (D) in the above-mentioned content range, a high-quality molded product with less occurrence of shavings can be obtained as a molded product. The mechanism by which this effect is obtained is not clear, but it is presumed that the component (D) acts as a plasticizer for the polyamide resin (components (A) and (B)) (however, the effect is presumed). Not limited to this).

The 98% sulfuric acid relative viscosity ηr (based on JIS K6920) of the polyamide resin composition of the present invention is 2,500 to 2.83, more preferably 2,500 to 2.70, and more preferably 2.55 to 2.70. preferable. By setting the relative viscosity to 2.50 or more, the hinge characteristics of the molded product can be improved, and by setting the relative viscosity to 2.83 or less, the flame retardancy can be further improved.

The polyamide resin composition of the present invention has a number of breaks (breaks) of 4000 or more and 5000 or more in a hinge test in which a test piece having a portion having a thickness of 0.4 mm and a width of 5 mm is bent 180 degrees. It is preferably present, and more preferably 5500 times or more. The number of breaks can be measured by the method described in Examples described later.

(Other resins)
If necessary, other resins may be added to the polyamide resin composition of the present invention as long as the object of the present invention is not impaired. Examples of other resins include polytetramethylene adipamide (polyamide 46), polyhexamethylenecyclohexylamide (polyamide 6C), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), and the like. Polyundecalactum (polyamide 11), polydodecalactum (polyamide 12), polyhexamethylene isophthalamide (polyamide 6I), polyhexamethylene terephthalamide (polyamide 6T), polynonane methylene terephthalamide (polyamide 9T), polydodecamethylene Examples thereof include terephthalamide (polyamide 12T), polymethaxylylene adipamide (polyamide MXD6), and polyamide copolymers containing at least two different polyamide-forming components, as well as mixtures and various elastomers thereof.

[Other ingredients]
The polyamide resin composition of the present invention contains a commonly used filler, for example, inorganic fibers such as glass fiber and carbon fiber, mica, talc, clay mineral, as long as the object of the present invention is not impaired. , Alumina, silica, and inorganic fillers such as apatite, aluminum hydroxide, magnesium hydroxide, zinc borate, zinc tinate, zinc hydroxytinate, ammonium polyphosphate, succinoguanamine, melamine polyphosphate, melamine sulfate, phthal Flame retardants such as melamine acid and aluminum hydroxide, pigments and colorants such as titanium white and carbon black, metal phosphite salts such as sodium hypophosphite, heat stabilizers typified by hindered phenols and hindered amines, 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 component (A), the component (B), and the component (C) (if necessary, the component (D), hereinafter, the component (D)) are used. Although all of them may be melt-kneaded at once (explaining the case of containing), from the viewpoint of dispersibility of the melamine cyanurate-based flame retardant of the component (C), a part of the component (C) is melted and all the remaining components are melted. After kneading, it may be further melt-kneaded. Further, a masterbatch containing the components (A) to (D) may be prepared in advance and melt-kneaded using this masterbatch.

The shape of the polyamide resin of the component (A) and the component (B) is not particularly limited, but is preferably in the form of pellets. In this case, from the viewpoint of equipment simplification, the surfactant of the component (D) is spread on the surface of the polyamide resin pellets of the components (A) and (B), and then the melamine of the component (C) is further spread. It may be melt-kneaded after forming a blend in which a cyanurate-based flame retardant is spread. Even in such a configuration, from the viewpoint of dispersibility, a part of the component (C) may not be spread, and all the remaining components may be melt-kneaded and then further melt-kneaded.

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., the TEX series manufactured by Japan Steel Works, Ltd., and the L of the twin-screw extruder. / 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.

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, a loss-in-weight screw feeder is preferable because it has less fluctuation error in raw material supply. 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.

From the viewpoint of productivity and suppression of thermal deterioration, the temperature at the time of kneading and melting is preferably 5 to 30 ° C. higher than the melting point of the component (A), and more preferably 5 to 20 ° C. higher. ..

[Molded product]
The molded product obtained by molding the polyamide resin composition of the present invention has high flame retardancy, hinge characteristics, and features that suppress variations in hinge characteristics. Therefore, electricity for sockets, switches, cases, covers, etc. It is suitable as an injection molded product used as an electronic part, an automobile interior / exterior part, an automobile electrical component, or the like, and as a pellet as a molding material for these injection molded products. In particular, it is suitable for connector parts and clips having a hinge portion. In particular, the high flame retardancy of thin-walled parts and the small variation in hinge characteristics can contribute to the recent demand for thinning of molded products, and the small variation in hinge characteristics can reduce the defective rate of molded products. The industrial significance is very large because it can contribute.

The present invention will be described in more detail with reference to Examples and Comparative Examples.
(Material property evaluation method)
The physical property evaluations described in the following Examples and Comparative Examples were carried out as follows.

<Sulfuric acid relative viscosity ηr>
The sulfuric acid relative viscosity ηr (25 ° C., 1 g / 100 ml) of the component (A), the component (B) and the polyamide resin composition was measured according to JIS K6920.

<Melting point>
The melting point of the component (A) was measured using a differential calorimetry device DSC-7 manufactured by PerkinElmer. The temperature raising and lowering conditions were 20 ° C./min, respectively. About 10 mg of the sample was heated from room temperature, the endothermic peak temperature (Tm1) was observed, and then the sample was held at a temperature 20 to 50 ° C. higher than Tm1 for 3 minutes. Then, after cooling the sample to room temperature, the temperature was raised again and the endothermic peak was observed. The temperature indicated by the peak top was taken as the melting point.

<Medium diameter>
The median diameter of the component (C) was measured using a laser diffraction type particle size distribution measuring device 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 horizontal axis is the particle size, and the vertical axis is the frequency (mass). The particle size at which the cumulative mass is 50% when the total cumulative mass of this frequency is 100% is defined as the medium diameter (D50). did.

(Preparation of each ingredient)
[Component (A): Polyamide 66/6 resin, Polyamide 66 resin]
(A-1) Component: Polyamide 66/6 Resin Necessary for producing 18.8 kg of a copolymerized polyamide 66/6 containing 90% by mass of a bonding unit corresponding to polyamide 66 and 10% by mass of a bonding unit corresponding to polyamide 6. 39.2 kg of a 50 mass% AH salt (isomol salt of adipic acid and hexamethylenediamine) aqueous solution and 1.9 kg of ε-caprolactam were placed in an 80 liter autoclave and stirred well. After sufficient substitution with nitrogen, the temperature was raised from room temperature to 220 ° C. At this time, the pressure in the autoclave became 1.8 MPa in terms of gauge pressure, but heating was continued for 1 hour while removing water from the system so that the pressure did not exceed 1.8 MPa. After that, when the internal temperature reaches 270 ° C, the pressure is lowered to atmospheric pressure over 60 minutes while removing water from the system, then the heating is stopped, the polymer is discharged in a strand shape from the lower nozzle, and the cutter is cooled with water. It was cut into columnar pellets having a diameter of 3 mmφ × 3 mm in length to obtain granules of a copolymerized polyamide 66/6 resin (mass ratio of copolymerized components 66: 6 = 90:10 ηr: 2.63 melting point 245 ° C.). ..

(A-2) Component: Polyamide 66/6 resin When the internal temperature of the autoclave reaches 270 ° C., the time for lowering the pressure to atmospheric pressure while removing water from the system is set to 45 minutes, but (a). The same procedure as in -1) was carried out (mass ratio of copolymerizable components 66: 6 = 90:10 ηr: 2.2 melting point 245 ° C.).

(A-3) Component: Polyamide 66/6 resin When the internal temperature of the autoclave reaches 270 ° C, the time for lowering the pressure to atmospheric pressure while removing water from the system is set to 75 minutes, but (a) The same procedure as in -1) was carried out (mass ratio of copolymerizable components 66: 6 = 90:10 ηr: 2.9 melting point 245 ° C.).

(A-4) Component: Polyamide 66 Resin 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 stirrer 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 relative viscosity of sulfuric acid of the polyamide 66 resin was about 2.73.
After the completion of the polymerization in the autoclave, the polyamide 66 resin was discharged in a strand form from the lower nozzle, and was subjected to water cooling and cutting to obtain a pellet-shaped polyamide 66 resin (ηr: 2.73).

[Component (B): Polyamide 6 resin]
(B-1): Polyamide 6 Ube Industries SF1013A Sulfuric acid relative viscosity 2.6
(B-2): Polyamide 6 Ube Industries, Ltd. 1010X1 Sulfuric acid relative viscosity 2.0
(B-3): Polyamide 6 Ube Industries, Ltd. 1030B Sulfuric acid relative viscosity 4.4

[(C) component: melamine cyanurate flame retardant]
(C-1): Melamine cyanurate medium diameter (D50): 2.6 μm
(C-2): Melamine cyanurate medium diameter (D50): 6.5 μm

[Component (D): Surfactant]
(D-1) PEM: Polyoxyethylene monolaurate Emanon (registered trademark) 1112 manufactured by Kao Corporation

[Example 1]
Using (a-1) polyamide 66/6 copolymer, (b-1) polyamide 6 resin, (c-1) melamine cyanurate, and loss-in weight feeder (LWF-D5 manufactured by K-TRON), It was supplied to the first supply port of a twin-screw extruder (TEM35BS manufactured by Toshiba Machine Co., Ltd., twin-screw co-directional screw rotary type, L / D = 47.6). Extrusion was performed at a barrel temperature of 260 ° C., a discharge rate of 30 kg / hr, and a screw rotation speed of 150 rpm. The screw of the extruder was provided with two kneading blocks. 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 2-9, Comparative Examples 1-7]
Polyamide resin composition pellets of Examples 2 to 9 and Comparative Examples 1 to 7 were prepared in the same manner as in Example 1 except that the composition of each component was as shown in Table 1. In Example 9, the barrel temperature was 270 ° C.

(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.
<Sulfuric acid relative viscosity measurement>
1.00 g of the resin composition cut out from the polyamide resin composition pellets produced in each Example and Comparative Example was dissolved in 100 g of 98% concentrated sulfuric acid, and measured at 25 ° C. according to JIS K6920.

<Mass ratio of 66 units of polyamide / 6 units of polyamide in the resin composition>
The pellet was dissolved in formic acid deuterated and ¹³ C-NMR was measured. At this time, the molar ratio of the polyamide 66 and the polyamide 6 was calculated from the peak area ratio of the carbon derived from the polyamide 66 and the polyamide 6, and further multiplied by the molecular weight to be converted into a mass ratio to obtain the mass ratio.

<Average particle size of component (C)>
A plane perpendicular to the long side of the columnar pellets of the resin composition obtained in Examples and Comparative Examples was cross-sectioned, and the cross section was observed at a magnification of 3000 times using a scanning electron microscope. The average particle size was measured using image analysis software (Image-Pro Plus 5.0J manufactured by Media Cybernetics).

<Tensile elongation>
Polyamide resin composition pellets are injected using an injection molding machine (PS40E manufactured by Nissei Resin Co., Ltd.) at a cylinder temperature of 270 ° C. and a mold temperature of 80 ° C. under injection molding conditions of 25 seconds for injection and 10 seconds for cooling. It was molded to obtain an ISO test piece having a thickness of 4 mm. Using the obtained ISO test piece, the tensile elongation was measured according to ISO527-1.

<Hinge characteristics / hinge standard deviation / low temperature hinge>
The polyamide resin composition pellets produced in each Example and Comparative Example are shown in FIGS. 1 and 2 using an injection molding machine (manufactured by Nissei Kogyo Co., Ltd .: PS40E cylinder temperature 270 ° C., mold temperature 80 ° C.). The hinge molded body 1 was molded. FIG. 1 is a top view of the hinge molded product 1, and FIG. 2 is a side view of the hinge molded product 1. The hinge molded product 1 includes a hinge portion 22. For the hinge molded product 1 of each example produced, the hinge portion 22 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 hinges were measured, and the average value of 15 hinges was used as the hinge characteristic value and the standard deviation was used as the index of variation. Those that did not break even if the hinge characteristic value was 4000 times were accepted. In addition, the standard deviation was evaluated according to the following criteria.
A: Less than 2000 B: 2000 or more and less than 4000 C: 4000 or more As a low temperature hinge characteristic, after the hinge molded body 1 is allowed to stand in an environment of 0 ° C. for 2 hours, the test piece is bent 180 ° by hand to form 20 pieces. The number of broken test pieces was counted and evaluated as follows.
A: Number of breaks 0 to 5 B: Number of breaks 6 to 10 C: Number of breaks 11 or more

<Flame retardant>
Using the pellets of the resin composition produced in Examples and Comparative Examples, they were supplied to a screw in-line injection molding machine set at 270 ° C., and tested for UL-94 vertical combustion test measurement under the condition of a mold temperature of 80 ° C. The pieces were injection molded (thickness: 0.35 mm and 0.71 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.

As shown in Table 1, according to the present invention, it is possible to improve flame retardancy and hinge characteristics, and also to improve variations in hinge characteristics.

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.

1 Hinge molded body 22 Hinge part

Claims (9)

A polyamide resin composition containing (A) a polyamide 66/6 copolymer, (B) a polyamide 6 resin, and (C) a melamine cyanurate-based flame retardant, which is the sum of the components (A) and (B). The polyamide 66/6 copolymer of the component (A) contains 4 to 8 parts by mass of the component (C) with respect to 100 parts by mass , and the polyamide 66 unit 50 to 95% by mass and the polyamide 6 unit 5 to 50 mass%. % consists, the polyamide mass ratio of the polyamide 66 units / polyamide 6 units of the resin composition is 88 / 12-73 / 27, 98% sulfuric acid relative viscosity ηr of the polyamide resin composition (JIS K6920 compliant) 2. 50 to 2.83, a polyamide resin composition in which the average particle size of the component (C) in the polyamide resin composition is 1.0 μm or less. 0.1 to 1.0 mass by mass of a surfactant containing (D) a fatty acid ester of at least one polyalkylene polyhydric alcohol with respect to 100 parts by mass of the total of the component (A) and the component (B). The polyamide resin composition according to claim 1, which comprises a part. The polyamide resin composition according to any one of claims 1 or 2 , wherein the component (A) has a 98% sulfuric acid relative viscosity ηr (based on JIS K6920) of 2.3 to 2.9. The polyamide resin composition according to any one of claims 1 to 3 , wherein the component (B) has a 98% sulfuric acid relative viscosity ηr (based on JIS K6920) of 2.1 to 2.7. The polyamide resin composition according to any one of claims 1 to 4 , wherein the 98% sulfuric acid relative viscosity ηr (JIS K6920 compliant) of the polyamide resin composition is 2.50 to 2.70. The component (D) is polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate. The polyamide resin composition according to any one of claims 2 to 5 , which is at least one selected from the group consisting of polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan trioleate. .. A molded product obtained by molding the polyamide resin composition according to any one of claims 1 to 6 . The molded body according to claim 7 , which is a connector component including a hinge portion. The molded product according to claim 7 , which is a clip.