JP2001323150A - Conductive resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive resin composition comprising compounding a thermoplastic resin with conductive carbon black, and particularly the composition which is possible to improve dispersion properties of the conductive carbon black. SOLUTION: The conductive resin composition comprises (a) a thermoplastic aromatic polycarbonate, (b) a thermoplastic polyalkylene phthalate and (c) the conductive carbon black which has n-dibutyl phthalate (DBP) oil absorption of 100-400 ml/100 g, and the component (b) being 1-10 pts.mass per 100 pts.mass of the component (a), and the component (c) being 5-20 pts.mass per 100 pts.mass of the sum of the components (a)+(b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive resin composition comprising a conductive resin and a conductive carbon black, and more particularly to a conductive resin composition capable of significantly improving the dispersibility of the conductive carbon black. About.

[0002]

2. Description of the Related Art In general, a thermoplastic resin is an electrically insulating substance, but is used for a material for an electric / electronic component which requires conductivity (for example, antistatic property, electromagnetic shielding property, etc.). There are many. In general, as a method for imparting conductivity to a thermoplastic resin, a compounding of a conductive material is generally performed, and particularly, a compounding of conductive carbon black is well known.

[0003] The provision of conductivity by carbon black greatly affects the dispersion state of carbon black in a resin matrix, and it is necessary for carbon black to form a linked structure in the resin in order to exhibit conductivity. In addition, it is necessary to mix carbon black in the resin matrix in a high concentration.

[0004] However, when a large amount of carbon black is blended, there is a concern that the mechanical strength and moldability of the resin may be reduced. In addition, when a resin composition containing carbon black is molded and processed as a member for electric / electronic parts, it is difficult to uniformly disperse the conductive carbon black, and a high-concentration portion of the carbon black locally in the resin ( Agglomerates with a diameter of 0.1 mm or more)
When the agglomerate is broken by some external factor, there is a problem that carbon black scatters and contaminates electric / electronic parts. From such a viewpoint, there is a demand for a conductive resin composition that improves the dispersibility of carbon black and does not scatter carbon black when molded.

On the other hand, in order to control the dispersibility of the conductive black, it has been known to mix a conductive carbon black with a polymer alloy of a thermoplastic resin and a polyester resin (see, for example, JP-A-63-207855). No.
JP-A-2-196854, JP-A-5-28714
No. 3, JP-A-6-41414, JP-A-7-3
No. 30925). However, each of these publications is common in that the conductive resin composition of the present invention is a conductive resin composition and the like, but differs in the configuration and technical idea.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems and the like, and is intended to solve the problem without impairing the mechanical properties and moldability of a thermoplastic resin.
An object of the present invention is to provide a conductive resin composition capable of improving the dispersibility of carbon black.

[0007]

The present inventors have conducted intensive studies to improve the dispersibility of carbon black in a thermoplastic resin as a result of the above-mentioned conventional problems and the like. By blending a specific amount of polyalkylene phthalate and carbon black of specific physical properties, respectively, without impairing the mechanical properties and moldability of the thermoplastic aromatic polycarbonate, the connection structure that is the basis for carbon black to exhibit its conductivity The inventors have found that a highly dispersed conductive resin composition can be obtained while maintaining the composition, and have completed the present invention. That is, the conductive resin composition of the present invention includes the following [1] and [2]. [1] A conductive resin composition containing the following components (a), (b) and (c), wherein component (b) is 1 to 10 parts by mass relative to 100 parts by mass of component (a). A conductive resin composition, wherein the component (c) comprises 5 to 20 parts by mass with respect to 100 parts by mass in total of the component (a) + the component (b). (A) thermoplastic aromatic polycarbonate (b) thermoplastic polyalkylene phthalate (c) n-dibutyl phthalate (DBP) oil absorption of 10
Conductive carbon black of 0 to 400 ml / 100 g [2] The thermoplastic polycarbonate of the component (a) comprises the following components (a-1) and (a-2), and
(A-1) component / (a-2) component is 50/50 by mass ratio.
The conductive resin composition according to the above [1], wherein the composition is from 90/10. (A-1) Melt flow rate (MFR) is 2 to 10 g
(A-2) a melt flow rate (MFR) of 15 to 50
g / 10min thermoplastic aromatic polycarbonate

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The conductive resin composition of the present invention comprises
(C) a thermoplastic aromatic polycarbonate of the component and a polyalkylene phthalate resin of the component (b);
N-dibutyl phthalate (DBP) oil absorption of the component is 10
0 to 400 ml / 100 g of conductive carbon black, wherein the component (b) is 1 to 10 parts by mass with respect to the component (a) 100 parts by mass. And the above-mentioned component (c) is 5 to 20 with respect to a total of 100 parts by mass of the component (a) + the component (b).
It is characterized by consisting of parts by mass.

As the thermoplastic aromatic polycarbonate of the component (a) used in the present invention, those produced by a solution method or a melting method of a dihydric phenol and a carbonate precursor are usually mentioned. Representative examples of dihydric phenols include bisphenol A [2,2-bis (4-hydroxyphenyl) propane] and bis (4-hydroxyphenyl)
Methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,
2-bis (4-hydroxy-3-methylphenyl) propane and the like. Preferred dihydric phenols are bis (4-hydroxyphenyl) alkane compounds, especially bisphenol A. These dihydric phenols can be used alone or in combination of two or more.
Examples of the carbonate precursor include carbonyl halide, carbonate, and haloformate. Representative examples include phosgene, diphenyl carbonate, dihaloformates of dihydric phenols, and mixtures thereof. Furthermore,
In the production of the aromatic polycarbonate, a suitable molecular weight modifier, a branching agent, a catalyst and the like can be used.

In the thermoplastic aromatic polycarbonate thus obtained, the thermoplastic aromatic polycarbonate of the component (a) in the present invention is preferably JI
Temperature 300 according to the method of SK-7210-1976
° C, melt flow rate (M
FR) of 2 to 50 g / 10 min may be used alone, but more preferably, two types of thermoplastic aromatic polycarbonates having different MFRs are mixed from the viewpoint of further improving the conductivity. It is desirable to do. That is, MF
R is 2 to 10 g / 10 min, preferably 2 to 5 g / 10 min under the above measurement conditions.
Is 15 to 50 g / 10 min, preferably 20 to 40 g /
10 minutes thermoplastic aromatic polycarbonate [(a-2)
Component) and the mass ratio (a-1) component /
It is desirable that the component (a-2) be mixed at 50/50 to 90/10, more preferably at 60/40 to 80/20. If the ratio of the component (a-1) is too large, (90/1)
0), the dispersibility of the carbon black is inferior due to the high viscosity of the resin during kneading. Conversely, if the component (a-1) is too small (less than 50/50), the mechanical strength of the resin composition And the viscosity of the resin is too low, making molding difficult. In addition, (a-1) and (a-
The ratio of MFR in 2) is desirably 2 to 20 (component (a-2) / component (a-1)).

The thermoplastic polyalkylene phthalate of the component (b) used in the present invention is formed by polycondensation of various phthalic acids or ester-forming derivatives thereof and alkylene glycol as main components, and has a main structure. It is a resin made of a saturated polyalkylene phthalate, and may be a copolymer containing other components. Examples thereof include polyalkylene phthalate homopolymers and copolymers such as polybutylene terephthalate, polybutylene terephthalate isophthalate copolymer, polyethylene terephthalate, and polyethylene terephthalate isophthalate copolymer. The molecular structure is not particularly limited. In the case of a copolymer, the molecular structure may be random, block, or any molecular structure such as linear, branched, or crosslinked. Furthermore, there is no particular limitation on the degree of polymerization, as long as it has moldability. Preferably, the o-chlorophenol solution has an intrinsic viscosity of 0.5 to 1.5 under measurement conditions of 25 ° C. Things are desirable.

The conductive carbon black of the component (c) used in the present invention must be a carbon black having an oil absorption of n-dibutyl phthalate (DBP) of 100 to 400 ml / 100 g. This DBP oil absorption is 400m
If it is larger than 1/100 g, the dispersion state of carbon deteriorates, a large amount of agglomerates are present when the resin composition is molded, and the DBP oil absorption is 100 ml / 10
If the amount is less than 0 g, the effect of imparting conductivity is inferior, which is not preferable. As carbon black having such properties, those commercially available as conductive carbon black, for example, Ketchen Black EC manufactured by Lion Corporation,
Production of synthesis gas containing hydrogen and carbon monoxide by partially oxidizing hydrocarbons such as naphtha in the presence of hydrogen and oxygen, including Vulcan XC-72 manufactured by Cabot Corporation and Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd. Carbon black having the above characteristics, which is a by-product of the above-described process, or carbon black having the above characteristics obtained by oxidizing or reducing the same.

The blending amount of the thermoplastic polyalkylene phthalate of the component (b) must be 1 to 10 parts by mass with respect to 100 parts by mass of the thermoplastic aromatic polycarbonate of the component (a). More preferably, it is 2 to 5 parts by mass. When the blending amount of the thermoplastic polyalkylene phthalate exceeds 10 parts by mass, the mechanical properties of the resin composition are inferior. Conversely, when the blending amount of the thermoplastic polyalkylene phthalate is less than 1 part by mass, the dispersion of carbon black is reduced. The properties are inferior, which is not preferable. Further, the compounding amount of the carbon black as the component (c) is the same as the component (a) +
With respect to a total of 100 parts by mass of the resin composition of the component (b), 5
The amount is required to be 20 to 20 parts by mass, and more preferably 6 to 15 parts by mass. The amount of carbon black is 5
If the amount is less than 10 parts by mass, the effect of imparting conductivity to the molded body is reduced. It becomes difficult to uniformly disperse, which is not preferable.

The conductive resin composition of the present invention may contain known additives capable of imparting desired physical properties as long as the effects of the composition are not impaired, such as lubricants, lubricants, nucleating agents, dyes / pigments. And additives such as a release agent, various stabilizers, other thermoplastic resins, reinforcing agents, and fillers.

As a method for preparing the conductive resin composition of the present invention thus constituted, for example, various known methods can be used, but at least the above components (a) to (c) coexist. The kneading is performed by kneading the components (a) and (b), which are thermoplastic resins, while heating and melting them for 30 seconds or more. At this time, the order of blending the components (a) to (c) is not particularly limited as long as the above conditions are satisfied. Specifically, a method in which the components (a) to (c) are uniformly mixed in advance with a mixer such as a tumbler or a Henschel mixer, and then supplied to a single-screw or twin-screw extruder for melt-kneading, or A method in which the thermoplastic resins (a) and (b) are mixed in advance, supplied to a single-screw or twin-screw extruder and melt-kneaded, and then carbon black as the component (c) is supplied from a side feeder. (For example, the method disclosed in JP-A-7-53767), and after pelletizing, it may be subjected to molding or may be directly molded. Further, the kneading treatment temperature is a temperature 5 to 50 ° C. higher than the temperature at which the thermoplastic resin component melts,
Particularly preferably, the temperature is 10 to 30 ° C. higher than the melting point of the resin. If the treatment temperature is too high, it is not preferable because the resin is decomposed or an abnormal reaction is induced. Furthermore,
The melt-kneading time is preferably 30 seconds to 10 minutes, more preferably 1 to 5 minutes.

The conductive resin composition of the present invention can be easily obtained by the above-mentioned preparation method or the like. The obtained conductive resin composition is directly or via a pellet, injection molding, extrusion molding, transfer molding, by molding by a known molding method such as inflation molding, such as a sheet, tape, film or molded article Various conductors can be manufactured.

[0017]

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

The four types of thermoplastic aromatic polycarbonates (PC) having different MFRs shown in Table 1 below (PC)
~), The thermoplastic polyalkylene phthalate (PBT) of the component (b), and the carbon black of the component (d) having different DBP oil absorptions were produced according to the respective mixing ratios. That is, using a twin screw extruder NR-II 57 mm manufactured by Nakatani Machinery Co., Ltd., a thermoplastic resin [(a) + (b)] is supplied from the original hopper of the extruder by a quantitative feeder, and the resin is completely melted. At this point, the carbon black was forcibly supplied to the extruder through a side feeder by a quantitative feeder and kneaded to obtain a compound. After cooling, the compound was cooled and then pelletized using a pelletizer (diameter 2 mm, length 2 to 4 mm). And next,
Using the pellets, physical properties such as the amount of aggregates, volume resistance and impact strength were evaluated by the following methods. The results are shown in Table 1 below.

[Method of Measuring Aggregate Amount] A 100 μm film was obtained by inflation molding the obtained pellet. This film was cut into a size of 100 cm ² , and 0.2 mm observed when transmitted light was irradiated.
The number of the carbon aggregates was measured with a microscope, and the dispersibility of carbon black was evaluated according to the following evaluation criteria. The smaller the number of carbon aggregates, the better the dispersibility of carbon black. Evaluation criteria: ：: 3 or less ○: 4 to 5 △: 6 to 20 ×: 21 or more

[Method of Measuring Volume Resistance Value] The obtained pellets are injection-molded to obtain 75.0 mm × 75.0 m.
Specimens of mx 3.0 mm were prepared, and their volume resistivity was measured according to the measurement method of SRIS-2321. Note that the smaller the numerical value of the volume specific resistance value, the better the conductivity.

[Method for Measuring Izod Impact Strength] The obtained pellets are subjected to injection molding to obtain 65.0 mm × 12.
A specimen having a size of 7 mm × 3.2 mm (with a radius of curvature of 0.25 R notch) was prepared, and the Izod impact strength was measured in accordance with the measurement method of ASTM D256. The higher the value of the Izod impact strength, the better the mechanical properties.

[0022]

[Table 1]

As is clear from the results shown in Table 1, it was found that Examples 1-4 of the present invention can improve the dispersibility of carbon black without impairing the mechanical properties and conductivity. In particular, in Examples 1, 2 and 4, specific MF
It was found that more excellent results were obtained when two types of polycarbonates serving as R were used. On the other hand, in the case of Comparative Examples 1 to 4, which were out of the range of the present invention, it was found that a product satisfying all of mechanical properties, conductivity and dispersibility of carbon black could not be obtained.

[0024]

According to the present invention, there is provided a conductive resin composition in which the dispersibility of carbon black is improved without impairing the mechanical properties and moldability of the polycarbonate resin, and the conductivity.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yoshinobu Nagasawa 1-3-7 Honjo, Sumida-ku, Tokyo Inside Lion Corporation (72) Inventor Hideo Komatsu 1-3-7, Honjo, Sumida-ku, Tokyo F term in Lion Corporation (reference) 4J002 CF042 CF062 CF072 CG011 DA036 GQ02 5G301 DA18 DA42 DD08 DD10

Claims (2)

[Claims] 1. The following components (a), (b) and (c)
A conductive resin composition containing the component, wherein the component (b) is 1 to 10 parts by mass and the total of the component (a) + the component (b) is 100 parts by mass of the component (a). A conductive resin composition comprising the component (c) in an amount of 5 to 20 parts by mass with respect to 100 parts by mass. (A) thermoplastic aromatic polycarbonate (b) thermoplastic polyalkylene phthalate (c) n-dibutyl phthalate (DBP) oil absorption of 10
Conductive carbon black of 0 to 400 ml / 100 g 2. The thermoplastic polycarbonate of component (a) comprises the following components (a-1) and (a-2):
In addition, (a-1) component / (a-2) component is 50 by mass ratio.
The conductive resin composition according to claim 1, wherein the ratio is from 50/90 to 90/10. (A-1) Melt flow rate (MFR) is 2 to 10 g
(A-2) a melt flow rate (MFR) of 15 to 50
g / 10min thermoplastic aromatic polycarbonate