CN108003610B

CN108003610B - Polyamide resin composition and molded article thereof

Info

Publication number: CN108003610B
Application number: CN201711042996.2A
Authority: CN
Inventors: 井俊一朗; 野上绫
Original assignee: Asahi Kasei Corp
Current assignee: Asahi Kasei Corp
Priority date: 2016-11-01
Filing date: 2017-10-31
Publication date: 2020-07-03
Anticipated expiration: 2037-10-31
Also published as: JP6867782B2; CN108003610A; JP2018070808A

Abstract

The present invention relates to a polyamide resin composition and a molded article thereof. The invention provides a polyamide resin composition having high molding fluidity and a good balance between toughness and flame retardancy, and a molded article. A polyamide resin composition comprising (a) a polyamide and (b) a melamine cyanurate, wherein the proportion of a component having a molecular weight of 15000 or less in the polyamide (a) as determined by Gel Permeation Chromatography (GPC) is 15.0 to 30.0% by mass of the whole polyamide (a), and the proportion of a component having a molecular weight of 100000 or more is 4.0 to 8.0% by mass of the whole polyamide (a).

Description

Polyamide resin composition and molded article thereof

Technical Field

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

Background

Polyamide resins have been widely used for various parts such as automobile parts, electronic and electrical parts, and industrial machine parts because of their excellent properties such as moldability including mechanical properties. In particular, since it is excellent in toughness, it is used for products having a hinge portion such as a connector and a clip. In many cases, flame retardancy is required for these products. Particularly from the viewpoint of the environment, it is desirable to use a halogen-free flame retardant.

Typical examples of such flame-retardant polyamide resins include flame-retardant polyamide materials using melamine cyanurate, such as connectors and clips used 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.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 53-125459

Patent document 2: japanese laid-open patent publication No. 53-031759

Patent document 3: japanese laid-open patent publication No. 11-106645

Disclosure of Invention

Problems to be solved by the invention

In the above flame-retardant polyamide resin using melamine cyanurate, melamine cyanurate is not sufficiently compatible with a polyamide resin, but is filled in a composition in a dispersed form like an inorganic filler. Therefore, the polyamide resin composition filled with melamine cyanurate tends to have a reduced toughness.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a polyamide resin composition having improved flame retardancy and toughness and reduced variation in toughness (バラつき).

Means for solving the problems

The present inventors have conducted extensive studies to solve the above problems, and as a result, have found that flame retardancy and toughness can be improved and variation in toughness can be reduced by adjusting the molecular weight component amount of polyamide in a resin composition containing polyamide and melamine cyanurate to a specific range, thereby completing the present invention.

That is, the polyamide resin composition of the present invention is a resin composition containing (a) a polyamide in which the proportion of a component having a molecular weight of 15000 or less as determined by Gel Permeation Chromatography (GPC) is 15.0 to 30.0 mass% of the whole polyamide (a) and the proportion of a component having a molecular weight of 100000 or more is 4.0 to 8.0 mass% of the whole polyamide (a), and (b) melamine cyanurate.

(a) The polyamide preferably 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 of the present invention may further contain (c) a polyol and/or an ester derivative thereof.

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

The melamine cyanurate (b) is preferably contained in an amount of 2 to 20 parts by mass based on 100 parts by mass of the polyamide (a).

The polyamide resin composition of the present invention preferably contains 100 parts by mass of (a) a polyamide, 2 to 20 parts by mass of (b) melamine cyanurate, and 0.1 to 1.0 part by mass of (c) a polyol and/or an ester derivative thereof.

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

Further, it is preferable that the polyamide composition contains 100 parts by mass of (a) a polyamide, 2 to 20 parts by mass of (b) a melamine cyanurate, 0.1 to 1.0 parts by mass of (c) a polyol and/or an ester derivative thereof, and 0.05 to 2.0 parts by mass of (d) a higher fatty acid metal salt.

Preferably, 80% by mass or more of the polyamide (a) is polyamide 66.

(a) The polyamide is more preferably polyamide 66.

(a) The polyamide 66 preferably has a relative sulfuric acid viscosity η r of 2.65 to 2.88.

(a) The relative sulfuric acid viscosity η r of the polyamide 66 is more preferably 2.73 to 2.88.

The molded article of the present invention is obtained by molding the polyamide resin composition of the present invention.

Effects of the invention

The polyamide resin composition of the present invention is a polyamide resin composition containing (a) a polyamide and (b) melamine cyanurate, wherein the proportion of a component having a molecular weight of 15000 or less in the polyamide resin (a) determined by Gel Permeation Chromatography (GPC) is 15.0 to 30.0 mass% of the whole polyamide (a), and the proportion of a component having a molecular weight of 100000 or more is 4.0 to 8.0 mass% of the whole polyamide (a), and therefore, the polyamide resin composition can be suitably used for household electrical appliances, electronic components, automobile components, and the like, while improving flame retardancy and toughness and reducing variation in toughness without impairing mechanical properties, chemical resistance, good moldability, electrical properties, and the like inherent in the polyamide resin composition.

Drawings

Fig. 1 is a schematic plan view of a hinge molded body (ヒンジ molded body) used for evaluation of examples.

Fig. 2 is a schematic side view of a hinge molded body used for evaluation of examples.

Reference numerals

10 hinge-shaped body

12 hinge part

Detailed Description

The present invention will be described in detail below.

[ Polyamide resin composition ]

The polyamide resin composition of the present invention is a resin composition containing (a) a polyamide and (b) melamine cyanurate, wherein the proportion of a component having a molecular weight of 15000 or less in the polyamide resin (a) as determined by Gel Permeation Chromatography (GPC) is 15.0 to 30.0 mass% of the whole polyamide (a), and the proportion of a component having a molecular weight of 100000 or more is 4.0 to 8.0 mass% of the whole polyamide (a).

Hereinafter, each component will be described in detail.

[ (a) ingredient: polyamide

The polyamide used in the present invention is a polymer having an amide bond (-NHCO-) in the main chain, and examples thereof include: polycaprolactam (polyamide 6), polytetramethyleneadipamide (polyamide 46), polyhexamethyleneadipamide (polyamide 66), polyhexamethylenecyclohexanediamide (polyamide 6C), polyhexamethylenesebacamide (polyamide 610), polyhexamethylenedodecanediamide (polyamide 612), polyundecanolactam (polyamide 11), polydodecanolactam (polyamide 12), polyhexamethyleneisophthalamide (polyamide 6I), polyhexamethyleneterephthalamide (polyamide 6T), polyparanonanediamide (polyamide 9T), polyparadodecanediamine (polyamide 12T), polymetaxylxylylene adipamide (polyamide MXD6), and polyamide copolymers containing at least two different polyamide-forming components among them, and mixtures thereof.

Among the above-mentioned various polyamides, polyamide 66 is particularly suitable as a material for obtaining a member which is high in moldability and melting point and is required to have higher heat resistance. When two or more polyamides are used, from the viewpoint of moldability and mechanical properties at high temperatures, the polyamide containing the polyamide 66 component in an amount of more than 50 mass% is more preferable, the polyamide containing the polyamide 66 component in an amount of more than 80 mass% is further preferable, and the polyamide containing the polyamide 66 component in an amount of 100 mass% is most preferable.

< molecular weight of Polyamide in composition >

The polyamide used in the polyamide resin composition of the present invention can improve flame retardancy and toughness and reduce variation in toughness by adjusting the components having a molecular weight of 15000 or less and the components having a molecular weight of 100000 or more to specific amounts. Specifically, from the viewpoint of flame retardancy and molding stability, the amount of the component having a molecular weight of 15000 or less is 15.0 to 30.0% by mass, more preferably 15.0 to 20.0% by mass, based on the whole polyamide. The content having a molecular weight of 100000 or more is 4.0 to 8.0% by mass, and more preferably 4.5 to 8.0% by mass, from the viewpoint of flame retardancy and toughness.

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 reduction of variation in toughness and molding stability.

In order to adjust the molecular weight of the polyamide in the polyamide resin composition to a specific amount, it is preferable to control the molecular weight by, for example, the screw rotation speed and the screw configuration at the time of melt kneading in an extruder.

The molecular weight of the polyamide can be obtained by measurement using Gel Permeation Chromatography (GPC). The apparatus used was "HLC-8320 GPC" manufactured by Tosoh corporation, the detector used a differential Refractometer (RI), the solvent used Hexafluoroisopropanol (HFIP) in which 0.1 mol% of sodium trifluoroacetate was dissolved, and the column used "TSKgel-GMHHR-M" 2 and "G1000 HHR" 1 manufactured by Tosoh corporation. The sample concentration is 1 to 3(mg sample)/1 (mL solvent), and the insoluble matter is removed by filtration with a filter to obtain a measurement sample. Based on the obtained elution curve, the molecular weight of the polyamide was calculated in terms of polymethyl methacrylate (PMMA).

< viscosity of Polyamide >

The polyamide resin composition containing such a polyamide preferably contains a polyamide having a 98% sulfuric acid relative viscosity η r of 2.65 to 2.88, more preferably 2.73 to 2.88. the polyamide resin composition obtained therefrom tends to have an excellent balance between flame retardancy and toughness.

[ (b) component: melamine cyanurate

The (b) melamine cyanurate used in the present invention is an equimolar reaction product of melamine and cyanuric acid, and is obtained, for example, by: an aqueous melamine solution and an aqueous cyanuric acid solution are stirred and mixed at a temperature of about 90 ℃ to about 100 ℃ to react to obtain a product, and the product is precipitated and filtered. The obtained substance is a white solid, and is preferably used by pulverizing into fine powder.

In the present embodiment, the melamine cyanurate may contain unreacted melamine or cyanuric acid in an amount of 0.001 to 0.30 mass%. Such melamine cyanurate is commercially available, and industrially available products can be suitably used.

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

Here, the median particle diameter (D50) is a particle diameter when the mass of particles having a particle diameter larger than a certain particle diameter accounts for 50% of the mass of the entire granular material in the particle diameter distribution of the granular material as defined in JIS Z8901, and can be measured by, for example, a laser diffraction scattering method. Specifically, the particle diameter is plotted on the horizontal axis and the frequency (mass) on the vertical axis by the laser diffraction scattering method, and the particle diameter at which the cumulative mass reaches 50% when the sum of the cumulative masses at the frequency is 100% is determined as the median diameter.

The amount of melamine cyanurate added is 2 to 20 parts by mass, preferably 3 to 15 parts by mass, based on 100 parts by mass of polyamide. The amount of the melamine cyanurate is preferably 2 parts by mass or more from the viewpoint of flame retardancy, and preferably 20 parts by mass or less from the viewpoint of mechanical properties. Any known method can be used for blending the melamine cyanurate in the polyamide resin, but a method of kneading and blending in an extruder or the like is industrially preferred.

[ (c) ingredient: polyhydric alcohol and/or ester derivative thereof ]

The polyol and/or ester derivative thereof used in the present invention preferably contains at least one polyalkylene polyol and fatty acid ester thereof. Mention may be made of: glycols such as polyethylene glycol, polypropylene glycol, ethylene glycol, diethylene glycol, trimethylene glycol and propylene glycol, glycols such as 1, 4-butanediol, 1, 5-pentanediol and 1, 6-hexanediol, polyols such as glycerol and pentaerythritol, and fatty acid esters of polyalkylene polyols include, for example: esters of polyalkylene polyols such as polyethylene glycol, polypropylene glycol and polybutylene glycol with aliphatic carboxylic acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, cerotic acid, montanic acid, melissic acid, oleic acid and erucic acid, and derivatives thereof are industrially readily available. From the viewpoint of dispersibility of the component (b), polyethylene glycol and fatty acid esters of polyethylene glycol are preferable, and higher fatty acid (having 12 or more carbon atoms) esters of polyethylene glycol and derivatives thereof are more preferable. The amount of the polyhydric alcohol and/or ester derivative thereof added is usually 0.1 to 1.0 part by mass, more preferably 0.1 to 0.8 part by mass, based on 100 parts by mass of the polyamide (a). 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 preferably 1.0 part by mass or less from the viewpoint of flame retardancy.

Preferred higher fatty acid esters of polyethylene glycol include polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, and polyoxyethylene monooleate, and polyoxyethylene monolaurate, polyoxyethylene monostearate, and polyoxyethylene monooleate are particularly preferred.

Further, as preferred higher fatty acid ester derivatives of polyethylene glycol, there can be mentioned: polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, and polyoxyethylene sorbitan trioleate.

[ (d) ingredient: higher fatty acid metal salt ]

The higher fatty acid metal salt (d) used in the present invention includes sodium salts, lithium salts, calcium salts, magnesium salts, zinc salts, aluminum salts, and the like of higher aliphatic carboxylic acids having 9 or more carbon atoms such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, cerotic acid, montanic acid, melissic acid, oleic acid, erucic acid, and the like, and among these higher fatty acid metal salts, metal stearates, specifically calcium stearate, magnesium stearate, zinc stearate, and aluminum stearate are particularly preferable because flame retardancy of the finally obtained polyamide resin composition is not lowered. Further, calcium stearate and aluminum stearate are most preferable from the viewpoint of reducing gas generation during molding. The amount of the higher fatty acid metal salt added is usually 0.01 to 5 parts by mass, and particularly preferably 0.05 to 2.0 parts by mass, based on 100 parts by mass of the polyamide (a). The amount of the additive is preferably 0.01 parts by mass or more from the viewpoint of plasticization at the time of molding, and preferably 5 parts by mass or less from the viewpoint of gas generation and flame retardancy at the time of molding. 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 that can improve toughness and flame retardancy and reduce variation in toughness. The inventors surmised that these properties are due to a synergistic effect of the amount of molecular weight components of the polyamide and the dispersibility of the melamine cyanurate. Namely, it is estimated that: (a) the polyamide component (a) has a low molecular weight range (molecular weight of 15000 or less) showing an effect in terms of flame retardancy and molding stability (mainly at low injection pressure), and a high molecular weight range (molecular weight of 100000 or more) showing an effect in terms of toughness, and further, can exhibit these properties at a high level by improving the dispersibility of melamine cyanurate.

[ other ingredients ]

The polyamide resin composition of the present invention may contain, if necessary, various conventional elastomers and fillers within a range not impairing the object of the present invention, for example, inorganic fibers such as glass fibers and carbon fibers, inorganic fillers such as mica, talc, clay minerals, alumina, silica and apatite, flame retardants such as aluminum hydroxide, magnesium hydroxide, zinc borate, zinc stannate, zinc hydroxystannate, ammonium polyphosphate, succinylguanamine, melamine polyphosphate, melamine sulfate, melamine phthalate and aluminum phosphate, pigments such as titanium white and carbon black, colorants, metal phosphites such as sodium hypophosphite, heat stabilizers typified by hindered phenols, hindered amines, trialkyl phosphates, and phosphites, lubricants such as higher fatty acid metal salts, higher fatty acid amides, and higher fatty acid esters, various plasticizers, and various additives such as antistatic agents.

[ Process for producing 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), the component (c) and the component (d) may be melt-kneaded first, but from the viewpoint of the dispersibility of the melamine cyanurate as the component (b), a part of the component (b) may be added after melt-kneading all the remaining components, and further melt-kneaded.

(a) The shape of the component is not particularly limited, and is preferably granular. In this case, from the viewpoint of simplification of equipment, the component (c) may be spread (expanded) on the surface of the particles of the component (a), and then the component (b) and the component (d) may be further spread to obtain a blend, followed by melt-kneading.

In the method for producing the polyamide resin composition of the present invention, the method of melt-kneading is not particularly limited, and when the component (a), the component (b), the component (c), and the component (d) are mixed, it is preferable to perform melt-kneading by supplying the mixture to an extruder using at least one raw material supply device. For supplying each component to the extruder, different raw material supply devices may be used, or one raw material supply device may be used.

The extruder is not particularly limited, and a twin-screw extruder is preferred. Specific examples of the twin-screw extruder include ZSK series manufactured by COPERION, TEM series manufactured by toshiba mechanical corporation, TEX series manufactured by japan steelworks, and the like, and the L/D (effective screw length/outer screw diameter) of the twin-screw extruder is preferably in the range of 20 to 60, and preferably 30 to 50. In order to adjust the molecular weight of the polyamide (a) in the resin composition to a specific range, it is preferable to perform extrusion under the condition that the resin temperature at the time of discharge from the tip nozzle of the extruder is 25 to 40 ℃ higher than the melting point of the polyamide as the main component, and the control can be performed by the screw rotation speed of the extruder and the number of kneading stages (a stage in which a plurality of screw elements having a high kneading effect called kneading disks are continuously formed).

The method of feeding the raw materials 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 bench feeder, a rotary feeder, a liquid supply pump, or the like can be used. Among these, the weight loss-compensating screw feeder is preferable because the variation error in the supply of the raw material is small. In addition, when a plurality of raw materials are charged into one raw material supply apparatus, at least two raw materials among the raw materials to be charged may be mixed by a mixer, a conical mixer, or the like and then charged.

[ molded article ]

The molded article obtained by molding the polyamide resin composition of the present invention has flame retardancy, toughness and molding stability, and is therefore suitable as an injection molded article for electrical and electronic parts such as sockets, switches, housings and caps, interior and exterior parts of automobiles, electrical and electronic parts of automobiles, and pellets as a molding material for these injection molded articles.

Examples

The present invention will be described in further detail with reference to examples and comparative examples.

(method of evaluating physical Properties of raw Material)

First, a method of evaluating the physical properties of the raw materials will be described. The evaluation of physical properties of the raw materials used in the examples and comparative examples was carried out in the following manner.

Relative viscosity of sulfuric acid

The polyamide 66 was measured for a relative viscosity of 98% sulfuric acid of η r in accordance with 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 GPC described below.

The device comprises the following steps: HLC-8320GPC, manufactured by Tosoh corporation "

A detector: differential Refractometer (RI)

Solvent: hexafluoroisopropanol (HFIP) dissolved with 0.1 mol% sodium trifluoroacetate

A chromatographic column: the elution curve was calculated by using 2 "TSKgel-GMHHR-M" and 1 "G1000 HHR" manufactured by Tosoh corporation in series and converting them into polymethyl methacrylate (PMMA).

< median particle diameter >

(b) The median particle diameter of the melamine cyanurate flame retardant as the component (A) was measured using a laser diffraction particle size distribution measuring apparatus (trade name "SALD-7000", manufactured by Shimadzu corporation). A material obtained by dispersing a sample 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) on the vertical axis, and the median diameter is the particle diameter at which the cumulative mass reaches 50% when the sum of the cumulative masses at the frequency is 100% (D50).

(preparation of Components)

[ (A) ingredient: polyamide

(a-1) component: polyamide 66

An aqueous solution 15 kg. containing 50 mass% of a monomer mixture each containing hexamethylenediamine and adipic acid in equimolar proportions was prepared, and then the above-mentioned aqueous monomer solution was charged into a 40L-capacity autoclave having a stirring device and a suction nozzle at the lower part thereof, and the aqueous monomer solution was sufficiently stirred at 50 ℃.

After completion of the polymerization in the autoclave, the polyamide 66 resin was discharged in a strand form from the lower nozzle, and water-cooled and cut to obtain polyamide 66 in the form of pellets (η r: 2.81, Mw/Mn: 1.98).

(a-2) polymerization was carried out in the same manner as for the component (a-1), and the polymerization time was adjusted so that η r became about 2.71, whereby granular polyamide 66(η r: 2.71, Mw/Mn: 1.97) was obtained.

(a-3) polymerization was carried out in the same manner as for the component (a-1), and the polymerization time was adjusted so that η r was about 2.75, whereby granular polyamide 66(η r: 2.75, Mw/Mn: 1.98) was obtained.

(a-4) polymerization was carried out in the same manner as for the component (a-1), and the polymerization time was adjusted so that η r was about 2.61, whereby granular polyamide 66(η r: 2.61, Mw/Mn: 1.98) was obtained.

(a-5): polyamide 6, SF1013A from Yu Ju xing Ltd

[ (b) component: melamine cyanurate

(b-1): melamine cyanurate, median particle size (D50): 10 μm

[ (c) ingredient: polyhydric alcohol and/or ester derivative thereof ]

(c-1): polyoxyethylene monolaurate, EMANON (registered trademark) 1112(PEM) manufactured by Kao corporation

(c-2): polyethylene glycol, PEG400(PEG) manufactured by Sanyo chemical Co., Ltd

[ (d) ingredient: higher fatty acid metal salt ]

(d-1): calcium stearate, calcium stearate manufactured by Nippon fat Co., Ltd

[ example 1]

Polyamide 66 (a-1), melamine cyanurate (b-1), PEM (c-1), and calcium stearate (d-1) were mixed and fed to a first feed port of a twin-screw extruder (ZSK-40 MC, cylinder number: 12, manufactured by COPERION K.K.) using a weight loss compensating feeder. The extrusion was carried out at a barrel temperature of 270 ℃, a discharge rate of 100 kg/hour and a screw rotation speed of 250 rpm. The screw of the extruder was provided with two mixing sections. The first kneading section thereof was located in the 4 th barrel of the extruder and was constituted to have, from the upstream side, 3L (length in the screw axis direction of the screws constituting the kneading section) R-KD (feed type: R-type kneading disks) of 12mm, 2N-KD (non-conveying type: N-type kneading disks) of 24mm L and 1L-KD (reverse feed type: L-type kneading disks) of 12mm L. The second kneading section was located in the 8 th barrel of the extruder and was constituted to have 2R-KD's with L of 12mm, 1N-KD's with L of 24mm and 1L-KD's with L of 12mm from the upstream side. The "kneading zone" as used herein means a zone in which a plurality of screw elements called kneading disks having a high kneading effect are continuously arranged.

Then, the polymer was discharged in a strand form from a tip nozzle of the extruder, and water-cooled and cut to obtain polyamide resin composition pellets.

Examples 2 to 5 and comparative example 1

Pellets of polyamide resin compositions of examples 2 to 5 and comparative example 1 were produced in the same manner as in example 1, except that the compositions of the respective components were set as shown in table 1.

[ comparative examples 2 to 5]

The kneading was carried out in the same manner as in example 1, except that the screw rotation speed of the extruder was changed to 200rpm and the second kneading zone (located in the 8 th barrel) was changed to the conveying zone. The conveying section is a section that is constituted only by a screw element of a feed type and does not have a kneading section.

(evaluation of Polyamide resin composition)

The polyamide resin composition pellets of each example and comparative example were evaluated. The evaluation items and the results thereof are shown in table 1. The evaluation methods of the evaluation items are as follows.

< molecular weight >

The quantitative determination and molecular weight distribution (weight average molecular weight (Mw)/number average molecular weight (Mn)) of the component having a molecular weight of 15000 or less and the component having a molecular weight of 100000 or more were measured by GPC as follows.

A detector: differential Refractometer (RI)

< thin thickness tensile test (thin meat slide ) (test) >)

The polyamide resin composition pellets were injection-molded using an injection molding machine (SE 50D, manufactured by Sumitomo heavy machinery industries, Ltd.) under injection molding conditions of a cylinder temperature of 270 ℃ and a mold temperature of 80 ℃ for 10 seconds and cooling for 10 seconds, to obtain test pieces having a thickness of 0.5 mm. The tensile elongation was measured using the obtained dumbbell test piece under the conditions of a chuck pitch of 55mm and a tensile rate of 50 mm/min. At this time, the standard deviation was calculated from the values of the tensile elongation of 10 test pieces.

< standard deviation of articulation >

The polyamide resin composition pellets were molded into the hinge molded article 10 shown in FIGS. 1 and 2 by using an injection molding machine (PS 40E, manufactured by Nichisu Kogyo Co., Ltd.) with a cylinder temperature of 270 ℃ and a mold temperature of 80 ℃. Fig. 1 is a plan view of the articulated compact 10, and fig. 2 is a side view of the articulated compact 10. The hinged molded body 10 has a hinge 12. The hinge molded bodies 10 of the respective examples were manufactured by repeating the operation of bending the hinge portion 12 to a position of approximately 180 ° and then returning to the original position (0 °) at a rate of 33 times/minute in an atmosphere of 23 ℃ and 50% RH using an automatic repeat hinge tester, and the fracture was measured by breaking at a stage after the bending. In the hinge test, 15 molded bodies were measured, and the standard deviation of the 15 molded bodies was used as an index of the unevenness (バラつき).

< stability of formation (spiral flow length) >)

The polyamide resin composition pellets were injection-molded using an injection molding machine (SE 50D manufactured by sumitomo heavy machinery industry co., ltd.) with a cylinder temperature of 270 ℃ and a mold temperature of 80 ℃ under conditions of injection for 10 seconds, cooling for 10 seconds, an injection speed of 200 mm/sec and an injection pressure of 40MPa, molded in a spiral flow mold having a width of 10mm and a thickness of 1mm, and the flow length was measured after 15 test injections (sheet てショット). For the molding stability, the flow lengths of the 1 st shot and the 5 th shot were measured and determined according to the following criteria.

(evaluation criteria)

A: the difference between the flow length of the 1 st injection and the 5 th injection is less than + -2 mm

B: the difference between the flow lengths of the 1 st injection and the 5 th injection is + -2 mm or more

< flame retardancy >

The polyamide resin composition pellets were injection-molded into UL-94 test pieces (thickness: 0.40mm, 0.80mm) for vertical burning test measurement using an injection molding machine (PS 40E, manufactured by Hitachi resin Co., Ltd.), with a cylinder temperature of 270 ℃ and a mold temperature of 80 ℃. Using 5 test pieces of different thicknesses molded in this manner, the flame retardancy was evaluated based on the UL-94 vertical burning test, and the flame retardancy V-0, V-1, V-2, and HB were evaluated.

As shown in table 1, according to the present invention, the flame retardancy and the toughness were excellent, and the variation in toughness was also reduced.

On the other hand, in comparative examples 1 and 2 in which the proportion of the polyamide component having a molecular weight of 100000 or more was less than 4.0 mass%, the hinge characteristics were good, but the tensile elongation was poor and the variation was large. In comparative examples 3 to 5 in which the proportion of the polyamide component having a molecular weight of 15000 or less was less than 15% by mass, the hinge characteristics and the tensile elongation were good, but the variation in the tensile elongation was large, and the flame retardancy and the molding stability were poor.

Industrial applicability

The polyamide resin composition of the present invention has high flame retardancy, and therefore is useful as industrial materials for various mechanical industrial parts, electrical and electronic parts, particularly connectors, clips, and the like.

Claims

1. A polyamide resin composition which is a resin composition containing (a) a polyamide and (b) melamine cyanurate, wherein,

the proportion of a component having a molecular weight of 15000 or less in the polyamide (a) as determined by Gel Permeation Chromatography (GPC) is 15.0 to 30.0% by mass of the whole polyamide (a), and the proportion of a component having a molecular weight of 100000 or more is 4.0 to 8.0% by mass of the whole polyamide (a).

2. The polyamide resin composition according to claim 1, wherein the polyamide (a) has a molecular weight distribution, i.e., a weight average molecular weight (Mw)/number average molecular weight (Mn), of 1.90 to 2.00.

3. The polyamide resin composition as claimed in claim 1 or 2, wherein the polyamide resin composition further comprises (c) a polyhydric alcohol and/or an ester derivative thereof.

4. The polyamide resin composition as claimed in claim 1 or 2, wherein the polyamide resin composition further contains (d) a higher fatty acid metal salt.

5. The polyamide resin composition as claimed in claim 3, wherein the polyamide resin composition further comprises (d) a metal salt of a higher fatty acid.

6. The polyamide resin composition according to claim 1 or 2, wherein the polyamide resin composition contains 2 to 20 parts by mass of the (b) melamine cyanurate with respect to 100 parts by mass of the (a) polyamide.

7. The polyamide resin composition according to claim 3, wherein the polyamide resin composition comprises 100 parts by mass of the (a) polyamide, 2 to 20 parts by mass of the (b) melamine cyanurate, and 0.1 to 1.0 part by mass of the (c) polyol and/or ester derivative thereof.

8. The polyamide resin composition according to claim 4, wherein the polyamide resin composition comprises 100 parts by mass of the (a) polyamide, 2 to 20 parts by mass of the (b) melamine cyanurate, and 0.05 to 2.0 parts by mass of the (d) metal salt of a higher fatty acid.

9. The polyamide resin composition according to claim 5, wherein the polyamide resin composition comprises 100 parts by mass of the (a) polyamide, 2 to 20 parts by mass of the (b) melamine cyanurate, 0.1 to 1.0 parts by mass of the (c) polyol and/or its ester derivative, and 0.05 to 2.0 parts by mass of the (d) higher fatty acid metal salt.

10. The polyamide resin composition according to claim 1 or 2, wherein 80% by mass or more of the polyamide (a) is polyamide 66.

11. The polyamide resin composition as claimed in claim 1 or 2, wherein the (a) polyamide is polyamide 66.

12. The polyamide resin composition as claimed in claim 10, wherein the polyamide 66 (a) has a relative sulfuric acid viscosity η r of 2.65 to 2.88.

13. The polyamide resin composition as claimed in claim 11, wherein the polyamide 66 (a) has a relative sulfuric acid viscosity η r of 2.65 to 2.88.

14. The polyamide resin composition according to claim 10, wherein the polyamide 66 (a) has a relative sulfuric acid viscosity of η r of 2.73 to 2.88.

15. The polyamide resin composition according to claim 11, wherein the polyamide 66 (a) has a relative sulfuric acid viscosity of η r of 2.73 to 2.88.

16. A molded article obtained by molding the polyamide resin composition according to any one of claims 1 to 15.