JP2006124659A - Cap for fuel tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a conductive polyamide-based resin composition and a cap for a fuel tank comprising the composition. <P>SOLUTION: The conductive polyamide-based resin composition is obtained by mixing (A) 95-40% by mass of a polyamide resin with (B) 5-30% by mass of conductive carbon black, (C) 10-40% by mass of an ethylene-α-olefin copolymer containing a reactive functional group to be reacted with a terminal group and/or an amide group of the main chain of the polyamide resin and (D) 1-10% by mass of a high-density polyethylene resin in which (A) the polyamide resin forms a continuous phase, (C) the ethylene-α-olefin copolymer becomes particles having ≤2 μm average particle diameter and is dispersed in the continuous phase of (A) the polyamide resin and ≥80% by mass of (B) the conductive carbon black is dispersed in (A) the polyamide resin phase being a continuous phase. The cap for a fuel tank comprises the conductive polyamide-based resin composition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polyamide-based conductive resin composition comprising a polyamide resin, conductive carbon black, and an olefin-based resin, and a method for producing the same. The present invention also relates to a fuel tank cap having excellent conductivity and excellent impact resistance and slidability.

Polyamide resin has excellent chemical resistance against gasoline and other organic solvents and alkaline liquids, and has high fluidity, heat resistance, and creep resistance, so it is used as an exterior material for automobiles and parts in engine rooms. It has been. In addition, carbon black, etc. is added to provide conductivity, suppress the generation and charging of static electricity, and have a function that can be discharged in a relatively short time. It is used as a part.
However, the polyamide resin has a drawback that the dimensional change becomes large due to water absorption, and there is a problem that impact strength is remarkably lowered by addition of carbon black or the like. It is well known to add carbon black to the polyamide resin in order to impart conductivity to the polyamide resin. However, increasing the amount of carbon black to improve the conductivity increases the fluidity and physical properties of the composition. Will be significantly impaired. Therefore, in order to improve fluidity and moldability, it has been proposed to blend carbon black, which imparts conductivity to polyamide resin, and modified ethylene copolymer, which suppresses dimensional changes due to water absorption and improves impact resistance. (See Patent Document 1).

  However, these methods improve the fluidity and moldability, but the impact resistance of the polyamide resin composition is not sufficiently improved. Since the impact resistance is low, it is considered that the modified ethylene copolymer dispersed in the polyamide resin composition has a relatively large dispersed particle diameter. Therefore, the conductivity and impact strength, which are required performance as a fuel tank cap, have not been achieved. In addition, since the soft modified ethylene copolymer is dispersed in the polyamide resin composition with a large dispersed particle size, it is a polyamide resin with originally excellent sliding characteristics. The dynamic characteristics are significantly impaired.

As a method for achieving both conductivity and impact resistance, a method of blending a carbon black dispersant has been proposed (see Patent Document 2). However, it is insufficient in terms of fluidity and suppression of dimensional change during water absorption, and there is a problem that the carbon black dispersant contaminates the mold during molding.
JP 58-93756 A Japanese Patent Laid-Open No. 11-180171

  The present invention was devised in view of the current state of the prior art described above, and its purpose is to provide a conductive polyamide resin composition in which carbon black is blended with a polyamide resin by specifying the composition and morphology structure. Another object of the present invention is to provide a polyamide resin composition capable of providing a molded article having high impact strength and excellent sliding characteristics, a method for producing the same, and a fuel tank cap comprising the same.

  As a result of diligent research to solve the above problems, the present inventors have dispersed an electrically conductive carbon black in a polyamide resin and further have an ethylene-α-olefin copolymer having a reactive functional group capable of reacting with the polyamide resin. Was found to be achieved by a conductive resin composition in which a polyamide resin is dispersed with an average particle size of 2 μm or less and a high-density polyethylene resin is blended, and the present invention has been completed.

That is, this invention is invention of the following (1)-(7).
(1) (A) 95-40% by mass of polyamide resin, (B) 5-30% by mass of conductive carbon black, (C) reactive functional group capable of reacting with end groups and / or amide groups of the main chain 10 to 40% by mass of an ethylene-α-olefin copolymer having a group, and (D) 1 to 10% by mass of a high-density polyethylene resin, (A) a polyamide resin forms a continuous phase, and (C) The ethylene-α olefin copolymer is present as particles having an average particle size of 2 μm or less (A) dispersed in the continuous phase of the polyamide resin, and (B) 80% by mass or more of the conductive carbon black is continuous. A polyamide-based conductive resin composition which is dispersed in the (A) polyamide resin phase which is a phase.
(2) The polyamide-based conductive resin according to (1), wherein the polyamide-based conductive resin composition has a volume resistivity of 1 × 10 ¹¹ Ω · cm or less and an Izod impact strength of 300 J / m or more. Resin composition.
(3) The polyamide conductive resin composition as described in (1) or (2), wherein the taper wear value of the polyamide conductive resin composition is 25 mg or less.
(4) (A) 95-40% by mass of polyamide resin, (B) 5-30% by mass of conductive carbon black, (C) reactive functional group capable of reacting with terminal groups and / or main chain amide groups In the method for producing a polyamide-based conductive resin composition comprising 10 to 40% by mass of an ethylene-α-olefin copolymer having a group and (D) 1 to 10% by mass of a high-density polyethylene resin, (A) polyamide Resin and (B) conductive carbon black are previously melt-kneaded, and then (C) ethylene-α olefin copolymer and (D) high-density polyethylene resin are further melt-kneaded, and a polyamide-based conductive resin composition Manufacturing method.
(5) (A) polyamide resin, (B) conductive carbon black, (C) an ethylene-α olefin copolymer having a reactive functional group capable of reacting with an end group of the polyamide resin and / or an amide group of the main chain And (D) a high-density polyethylene resin, (A) a polyamide resin forms a continuous phase, and (C) an ethylene-α-olefin copolymer becomes particles having an average particle diameter of 2 μm or less ( A) A polyamide-based conductive resin composition that exists as a dispersed phase in a continuous phase of a polyamide resin, and (B) 80% by mass or more of conductive carbon black is dispersed in a polyamide resin phase that is a continuous phase. A fuel tank cap comprising:
(6) The polyamide-based conductive resin composition is characterized in that a molded article obtained from the resin composition has a volume resistivity of 1 × 10 ¹¹ Ω · cm or less and an Izod impact strength of 300 J / m or more. The fuel tank cap according to (5).
(7) The fuel tank cap according to (5) or (6), wherein the polyamide-based conductive resin composition has a Taber abrasion value of 25 mg or less of a molded product obtained from the resin composition.

  The conductive resin composition of the present invention blends carbon black with a polyamide resin to impart conductivity and improve moldability, and retains excellent impact resistance and sliding properties. The conductive resin composition having such good characteristics can be used favorably for fuel system parts of automobiles, such as fuel tank caps, strainers, filters, valves and the like. Therefore, it is important to contribute to the industry. The fuel tank cap of the present invention is excellent in impact resistance and sliding properties in addition to the chemical resistance and heat resistance possessed by polyamide, and further has conductivity so that static electricity charged on the human body or clothes can be prevented for a certain period of time. It is possible to reliably discharge into the inside.

The present invention will be specifically described below.
The polyamide-based conductive resin composition of the present invention can be used in various fields, for example, a cap for a fuel tank, but the feature is mainly a constituent material, and the structure of the cap is not particularly limited.
The (A) polyamide resin of the present invention has an acid amide bond (—CONH—) in the molecule, and specifically includes ε-caprolactam, 6-aminocaproic acid, ω-enantolactam, 7-amino. Polymers or copolymers obtained from heptanoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone, α-piperidine, etc., or blends thereof, hexamethylenediamine, nonamethylenediamine, undecamethylenediamine, Examples include polymers or copolymers obtained by polycondensation of diamines such as dodecamethylenediamine and metaxylylenediamine and dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid, and sebacic acid, or blends thereof. However, it is not limited to these.

  These polyamide resins preferably have a number average molecular weight of 7,000 to 30,000. If the number average molecular weight is less than 7000, the toughness is lowered, and if it exceeds 30,000, the fluidity is lowered. (A) The compounding quantity of a polyamide resin is 95-40 mass%, More preferably, it is 90-50 mass%. If the polyamide resin is less than 40% by mass, the morphological structure in which the polyamide resin should be a continuous phase becomes unstable in the microstructure of the molded article made of the polyamide-based conductive resin composition, which is not preferable.

  The conductive carbon black (B) of the present invention is not particularly limited, and ketjen black, acetylene black, furnace black, channel black, and the like can be used. Among these, ketjen black is particularly preferable because it exhibits excellent conductivity with a small blending amount. (B) Although the compounding quantity of electroconductive carbon black is based also on the electroconductive degree made into the objective, 30-5 mass% is suitable.

These conductive carbon blacks need to be dispersed in an amount of 80% by mass or more of the blending amount in the polyamide resin forming the continuous phase of the polyamide-based conductive resin composition. For this purpose, the kneading step is extremely important, and functional groups such as carboxyl groups and hydroxyl groups existing on the surface of the carbon black particles are also important. By sufficiently kneading in the kneading process, the functional group on the surface of the carbon black acts to increase the affinity with the polyamide resin, and it becomes easy to disperse in the continuous phase of the polyamide resin. In the present invention, the kneading conditions and the functional group concentration on the surface of the carbon black are not particularly limited. In the molded product of the polyamide-based conductive resin composition, 80% by mass or more of the blending amount of the carbon black is a continuous phase. It is important that it is dispersed in the polyamide resin. Physical properties of impact strength and wear resistance with compositions such volume resistivity by the dispersion of the carbon black has superior conductivity below 1 × 10 ¹¹ Ω · cm can be obtained becomes good.

  Examples of the ethylene-α-olefin copolymer having a functional group capable of reacting with the terminal group of the polyamide resin (C) and / or the main chain amide group of the present invention include an ethylene / propylene copolymer and an ethylene / propylene / diene. Copolymer, ethylene / butene-1 copolymer, ethylene / octene-1 copolymer, ethylene / hexene-1 copolymer, ethylene / 4 methylpentene-1 copolymer, ethylene / cyclic olefin copolymer, etc. However, it is not limited to these. (C) As for the compounding quantity of an ethylene-alpha olefin copolymer, 10-40 mass% is preferable. When the blending amount is less than 10% by mass, the impact strength of the polyamide-based conductive resin composition becomes low. On the other hand, if it exceeds 40% by mass, the elastic modulus and strength of the composition are remarkably lowered, and the wear resistance is also deteriorated.

  The functional group capable of reacting with the end group of the polyamide resin and / or the amide group of the main chain in the (C) ethylene-α-olefin copolymer of the present invention is an amino group, a carboxyl group and / or a terminal group of the polyamide resin. A functional group capable of reacting with the amide group of the main chain, specifically, a carboxylic acid group, an acid anhydride group, an epoxy group, an oxazoline group, an amino group, an isocyanate group, etc. An anhydride group is preferred because it is most reactive. The amount of functional groups is natural, but the larger the reaction, the more the reaction with the polyamide resin proceeds, and the ethylene-α-olefin copolymer is dispersed with a finer particle size in the continuous phase of the polyamide resin. Improves impact resistance of objects. The method for producing an ethylene-α-olefin copolymer having these functional groups includes a method of reacting a compound having the above functional group in a step of producing the copolymer, a copolymer pellet and a compound having a functional group, etc. Although there is a method of mixing and kneading with an extruder or the like, the method is not limited thereto.

  It is important that the (C) ethylene-α olefin copolymer of the present invention has a morphological structure in which the average particle diameter is 2 μm or less and is dispersed in a polyamide resin as a continuous phase. The above morphological structure is obtained by reacting the polyamide resin and the ethylene-α-olefin copolymer in the production process of the composition. High impact properties with an Izod impact strength of 300 J / m or more can be obtained by finely dispersing an ethylene-α-olefin copolymer with an average particle size of 2 μm or less in the polyamide resin, and excellent sliding properties of the polyamide resin. A composition is obtained that does not significantly reduce

  The (D) high-density polyethylene of the present invention is polyethylene having a density of 0.96 or more, and is not particularly limited. (D) As for the compounding quantity of a high density polyethylene, 1-10 mass% is preferable. If the blending amount is less than 1% by mass, the effect of improving the wear resistance is small, and if it exceeds 10% by mass, the strength and impact resistance of the composition are deteriorated. In the composition of the present invention, the ethylene-α olefin copolymer dispersed in the polyamide resin and the high-density polyethylene are the same olefin resin and have good affinity, so the dispersibility in the composition is good. The polyamide-based conductive resin composition in which highly crystalline high-density polyethylene is finely dispersed exhibits excellent slidability and has a Taber abrasion value of 25 mg or less.

The morphological structure of the fuel tank cap made of the polyamide-based conductive resin composition of the present invention is extremely important. The dispersion average particle diameter of the ethylene-α olefin copolymer which constitutes a continuous phase in which the polyamide resin serves as a matrix and is finely dispersed by reacting with the polyamide resin is 2 μm or less. Further, carbon black is dispersed in an amount of 80% by mass or more in the polyamide resin which is a continuous phase depending on the functional group present on the particle surface and the kneading conditions. High density polyethylene can be uniformly dispersed by affinity with finely dispersed ethylene-α olefin copolymer. Since the volume resistivity of the molded product obtained from the resin composition with such a morphological structure is 1 × 10 ¹¹ Ω · cm or less, the Izod impact strength is 300 J / m or more, and the Taber abrasion value is 25 mg or less. Thus, a fuel tank cap having excellent electrical conductivity, high impact resistance and sliding properties can be obtained. In order to enable more severe use, more preferably, the volume specific resistance of the molded product obtained from the polyamide-based conductive resin composition is 1 × 10 ⁹ Ω · cm or less, and the Izod impact strength is 500 J / m or more. The Taber abrasion value is 22 mg or less.

  In addition to the components (A), (B), (C), and (D) described above, the polyamide-based conductive resin composition of the present invention has a weather resistance improving material used for ordinary polyamide-based resin compositions. Copper oxides and / or alkali metal halides, phenolic antioxidants, phosphorus antioxidants, mold release agents, crystal nucleating agents, lubricants, pigments, dyes and the like as light or heat stabilizers good.

  The polyamide-based conductive resin composition used for the fuel tank cap of the present invention cannot form a stable morphological structure simply by mixing the components and kneading them with an extruder. It is recommended to knead. A specific method for producing the polyamide-based conductive resin composition of the present invention includes (A) a polyamide resin (for example, a twin-screw extruder, a pressure kneader, a single-screw extruder, a melt reaction kettle, etc.) B) After the conductive carbon black is melt-kneaded and the conductive carbon black is uniformly dispersed in the polyamide resin, (C) the modified ethylene-α-olefin copolymer and (D) the high-density polyethylene. Further, if necessary, other additives are added and further melt-kneaded. By performing such two-stage melt kneading, the polyamide-based conductive resin composition having a morphological structure of the present invention can be stably produced. However, the production of the polyamide-based conductive resin composition of the present invention is not limited to such a specific blend and melt kneading method, and other blends and melt methods are used as long as the above composition and morphology structure are obtained. Thus, the composition of the present invention can be produced. For example, in a vent type twin-screw extruder with a supply port in the middle part, (A) polyamide resin and (B) conductive carbon black are charged into the hopper, which is the main supply part, and melted and kneaded, so (C) An ethylene-α olefin copolymer having a functional group and (D) high-density polyethylene are charged and melt-kneaded from the vent port, which is the supply port of the section, so that a series of continuous melt-kneading is performed. Inventive compositions can be produced. These specific production methods are not limited to the methods described herein, and other production methods can be used as long as the conductive carbon black is finely dispersed in the polyamide resin as described above. Thus, the composition of the present invention can be produced.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.
In addition, each characteristic and physical property value shown in the following examples and comparative examples were measured by the following test methods. The test piece was molded under the following conditions by an injection molding machine (Toshiba Machine Co., Ltd., IS80).
Resin temperature: 275 ° C
Mold temperature: 40 ℃
Injection pressure: 50 kg / cm ²
Injection time: 1 second Holding pressure: 60 Kg / cm ²
Holding time: 6 seconds Volume specific resistance: Terminals were connected to both ends perpendicular to the gate of a 100 mm × 100 mm, 2 mm thick plate obtained by injection molding and measured with a digital multimeter (manufactured by Advantest Corporation, TR-6843).
The measurement specimen was vacuum-dried at 70 ° C. for 12 hours and then seasoned in an atmosphere of 20 ° C. and 50% RH for 24 hours.
2. Izod impact strength: Measured according to ASTM D256 (notched).
3. Taber abrasion: Measured according to JIS K 7204 (wear wheel CS17, load 1000 g, rotation speed 1000 rotations).
4). Observation of morphological structure: A frozen section was prepared from the center of a 100 mm × 100 mm, 2 mm thick plate obtained by injection molding.
For measurement of the average particle size, a frozen section having a cross section perpendicular to the resin flow direction of the sample was prepared, dyed with a 5% phosphotungstic acid aqueous solution for 30 minutes, further subjected to carbon vapor deposition, and then passed through JEM2010 manufactured by JEOL. A photograph is taken by observing with an electron microscope at an acceleration voltage of 200 KV and a direct magnification of 5000 times. Subsequently, an average particle diameter is calculated | required by using the acquired photograph for an image analyzer. In this apparatus, when the observed image of the domain is elliptical, the diameter converted to a sphere is used as the particle diameter.
The location of carbon black is determined by counting the number of all carbon black particles present in the obtained photograph and the number of carbon black particles present in the continuous phase or dispersed phase with an image analyzer, and The percentage% of the number of black particles was mass%.

The raw materials of the compositions used in the examples and comparative examples were as follows.
(A) Toyobo Nylon T-840 (Toyobo Co., Ltd., nylon 6, relative viscosity 2.2)
(B) The following two types of carbon black were used.
B-1: Furnace Carbon C100 (manufactured by Lion Corporation)
B-2: Ketjen Carbon EC (manufactured by Lion Corporation)
(C) The modified ethylene-α olefin copolymer was modified with maleic anhydride, and the following two types were used.
C-1: Tuffmer (R) MH5010 (manufactured by Mitsui Chemicals, Inc.)
C-2: Tuffmer (R) MH5020 (manufactured by Mitsui Chemicals, Inc.)
(D) The following materials were used for the high density polyethylene.
D: High density polyethylene MME001 (manufactured by Mitsui Chemicals, Inc.)

(Examples 1 to 3 and Comparative Examples 1 and 2)
Examples 1 to 3 and Comparative Examples 1 and 2 are as follows.
In the production methods of Examples 1 to 3, each raw material was weighed and blended at the composition ratio shown in Table 1 in a one-step kneading process, and melted in a twin-screw extruder (Ikegai Iron Works Co., Ltd., PCM30) set at a cylinder temperature of 260 ° C. Kneaded into pellets. Next, the raw materials are weighed and blended at the composition ratio shown in Table 1 in this pellet and the two-stage kneading process, and melt-kneaded in a twin-screw extruder set at 260 ° C. in the same manner as in the first-stage kneading process. I got a thing. On the other hand, in Comparative Examples 1 and 2, all the raw material components having the composition ratios shown in Table 1 were metered and blended only in the two-stage kneading process without passing through the one-stage kneading process, and melted in the twin-screw extruder set at 260 ° C. as described above. Kneading was performed to obtain a polyamide-based conductive resin composition.

  In Examples 1 to 3, the polyamide resin and carbon black are melt-kneaded in a one-stage kneading process, and carbon black is dispersed in a polyamide resin that becomes a continuous phase with a morphological structure, and then a modified ethylene-α-olefin in a two-stage kneading process. The morphological structure of the present invention could be obtained by melt-kneading the copolymer and high-density polyethylene. In these polyamide resin compositions, high impact strength and excellent Taber abrasion value are obtained together with good conductivity. FIG. 1 shows an electron microscope photograph showing these morphological structures. It can be seen that almost all of the carbon black is dispersed in the polyamide resin phase, and the modified ethylene-α-olefin copolymer is uniformly dispersed with an average particle size of 2 μm or less.

  On the other hand, when all the composition components are blended and kneaded simultaneously in Comparative Examples 1 and 2, the morphological structure of the present invention is not obtained. Of particular note is that Example 1 and Comparative Example 1 have the same composition, but the Izod impact strength and the Taber abrasion value differ greatly. In the morphology structure of Comparative Example 1, carbon black is dispersed in both components of the continuous phase of the polyamide resin and the dispersed phase of the ethylene-α-olefin copolymer, and the dispersed particle size of the ethylene-α-olefin copolymer is also large. Because of such a morphological structure, it seems that Izod impact strength and Taber abrasion value deteriorated. In the kneading process, the functional group of the ethylene-α-olefin copolymer and carbon black have some effect, and the activity of the functional group of the ethylene-α-olefin copolymer has been lost. By doing so, it is presumed that the impact strength and wear resistance of the polyamide resin composition were significantly deteriorated. As is apparent from the examples and comparative examples, the polyamide-based conductive resin composition having the morphological structure of the present invention can have excellent conductivity, high impact strength, and excellent Taber abrasion value.

<Production of fuel tank cap>
A fuel tank cap mainly composed of a filler neck, a resin closure, and a resin shell using each pellet of the polyamide-based conductive resin composition obtained in Examples 1 to 3 and Comparative Examples 1 and 2 (FIG. 3). Both the resin closure and the resin shell (see) were manufactured by injection molding (injection molding machine: IS80, manufactured by Toshiba Machine Co., Ltd.). The molding conditions are as shown below.

Resin temperature: 275 ° C
Mold temperature: 40 ℃
Injection pressure: 50 kg / cm ²
Injection time: 1 second Holding pressure: 60 Kg / cm ²
Holding time: 6 seconds

The volume specific resistivity was measured for the resin shell (outer). That is, as shown in FIG. 6, the outer electrode (b) is squeezed with a counter electrode (b) having a conductive rubber sheet of 100Ω or less attached to the tip, and a high resistance meter (R- 8340) was connected, and the volume resistivity was measured at an applied voltage of 500V. As a result, the outer is sufficient volume resistivity as a cap for a fuel tank (1 × 10 ² ~1 using each pellet of the cap for the polyamide-based conductive resin composition of the present invention obtained in Examples 1 to 3 × 10 ⁹ Ω · cm) and good performance.

(Examples 1 'and 2' and Comparative Examples 1 'to 3')
In the production methods of Examples 1 'and 2' and Comparative Examples 2 'and 3', a twin screw extruder (Ikegai) in which each raw material was metered and blended at a composition ratio shown in Table 2 in a one-stage kneading process and the cylinder temperature was set to 260 ° C. Pellets were melt-kneaded with Iron Works Co., Ltd. (PCM30). Next, in the two-stage kneading step, each raw material was weighed and blended at a composition ratio shown in Table 2 and melt-kneaded with a twin-screw extruder set at 260 ° C. to obtain a polyamide-based conductive resin composition. On the other hand, in Comparative Example 1 ′, all the raw material components having the composition ratios shown in Table 2 were metered and blended in the two-stage kneading step, and melt-kneaded by a twin-screw extruder set at 260 ° C. in the same manner as described above to obtain a polyamide-based conductive resin. A composition was obtained.

  In Examples 1 ′ and 2 ′, the polyamide resin and carbon black are melt-kneaded in a one-stage kneading process, and the carbon black is dispersed in a polyamide resin to be a continuous phase. The polymer and high density polyethylene were melt kneaded. In the composition produced by such a production method, high impact strength and excellent taper wear value are obtained together with conductivity.

On the other hand, in Comparative Example 1 ′, all the composition components were blended and kneaded simultaneously. Of particular note is that Example 1 ′ and Comparative Example 1 ′ have the same composition, but the Izod impact strength and the taper wear value differ greatly. In Comparative Example 1 ′, all the components were mixed at the same time and melt kneaded, so that (B) the functional group on the particle surface of the conductive carbon black and the functional group (C) ethylene-α olefin copolymer were melt kneaded. Since the activity of the functional group imparted to the ethylene-α-olefin copolymer is lost, the reaction rate with the polyamide resin that should be reacted is reduced, so that the impact strength and wear resistance of the composition are significantly deteriorated. It is estimated that
Further, in Comparative Example 2 ′, since (D) high-density polyethylene is not blended, the taper wear value is significantly reduced. In Comparative Example 3 ′, when the blending amount of the (C) ethylene-α olefin copolymer having a functional group is reduced, the impact strength of the composition is naturally lowered.

  As is apparent from Examples and Comparative Examples, the polyamide-based conductive resin composition produced by the production method of the present invention can have excellent conductivity, high impact strength, and excellent Taber abrasion value.

  The polyamide-based resin composition of the present invention has excellent electrical conductivity and excellent impact resistance and sliding characteristics. Conductive resin compositions with such good properties can be used in a wide range of fields as automotive fuel system parts, such as fuel tank caps, strainers, filters, valves, etc., and contribute to the industry. Is big. In particular, the fuel tank cap of the present invention is excellent in mechanical properties such as Izod impact strength and Taber wear, and molding processability, and can reliably discharge static electricity charged on the human body or clothes within a predetermined time. .

The electron micrograph of the polyamide-type conductive resin composition of this invention. The electron micrograph of the polyamide-type conductive resin composition of the comparative example 1. Cross-sectional explanatory drawing of an example of the general cap used for fuel tanks, such as a motor vehicle. Cross-sectional explanatory drawing of an example of the general cap used for fuel tanks, such as a motor vehicle. Cross-sectional explanatory drawing of an example of the general cap used for fuel tanks, such as a motor vehicle. Measurement explanatory drawing of the volume resistivity of the resin-made shell (outer) based on ASTMD257.

Explanation of symbols

1a: Polyamide resin (continuous phase)
2a: Carbon black 3a: Modified ethylene-α-olefin copolymer particles (dispersed phase)
1b: Polyamide resin (continuous phase)
2b: carbon black 3b: modified ethylene-α-olefin copolymer particles (dispersed phase)
1: Filler neck 2: Cap 3: Resin closure 4: Cylindrical part 5: Screw part 6: Flange part 7: Seal ring 8: Top plate part 9: Flow hole 10: Valve body 11: Valve body holding plate 12: Coil spring 13: Spring seat plate 14: Resin shell 15: Fuel lid 16: Mounting plate 17: Mounting hole 18: Auto body 19: Fuel supply port 20: Body body 23: Retainer 23a: Engaging portion (female)
23b: Ring member 26: String-like conductor 34a: Engagement part (male type)

Claims (7)

  (A) Polyamide resin 95 to 40% by mass, (B) Conductive carbon black 5 to 30% by mass, (C) Reactive functional group capable of reacting with end group and / or main chain amide group of polyamide resin 10 to 40% by mass of an ethylene-α olefin copolymer and (D) 1 to 10% by mass of a high-density polyethylene resin are blended, and (A) a polyamide resin forms a continuous phase, and (C) ethylene-α. The olefin copolymer is present as particles having an average particle size of 2 μm or less (A) dispersed in the polyamide resin continuous phase, and (B) 80% by mass or more of the conductive carbon black is the continuous phase. (A) A polyamide-based conductive resin composition dispersed in a polyamide resin phase. The volume resistivity of the polyamide-based conductive resin composition is not more than 1 × 10 ¹¹ Ω · cm, and polyamide-based conductive resin composition according to claim 1, wherein the Izod impact strength of 300 J / m or more object.   3. The polyamide based conductive resin composition according to claim 1, wherein the taper wear value of the polyamide based conductive resin composition is 25 mg or less.   (A) Polyamide resin 95 to 40% by mass, (B) Conductive carbon black 5 to 30% by mass, (C) Reactive functional group capable of reacting with end group and / or main chain amide group of polyamide resin In the method for producing a polyamide-based conductive resin composition comprising 10 to 40% by mass of an ethylene-α-olefin copolymer and 1 to 10% by mass of (D) a high-density polyethylene resin, (A) a polyamide resin and ( B) Conductive carbon black is previously melt-kneaded, and then (C) an ethylene-α olefin copolymer and (D) high-density polyethylene resin are further melt-kneaded to produce a polyamide-based conductive resin composition Method.   (A) polyamide resin, (B) conductive carbon black, (C) an ethylene-α olefin copolymer having a reactive functional group capable of reacting with a terminal group and / or an amide group of the main chain of the polyamide resin, and ( D) A high density polyethylene resin is blended, (A) the polyamide resin forms a continuous phase, and (C) the ethylene-α olefin copolymer becomes particles having an average particle size of 2 μm or less. It consists of a polyamide-based conductive resin composition that exists as a dispersed phase in the continuous phase of the resin, and (B) 80% by mass or more of the conductive carbon black is dispersed in the polyamide resin phase that is the continuous phase. A fuel tank cap. The polyamide-based conductive resin composition is characterized in that the molded article obtained from the resin composition has a volume resistivity of 1 × 10 ¹¹ Ω · cm or less and an Izod impact strength of 300 J / m or more. Item 6. A fuel tank cap according to Item 5.   7. The fuel tank cap according to claim 5, wherein the polyamide-based conductive resin composition has a Taber abrasion value of 25 mg or less of a molded product obtained from the resin composition.