JPS5893756A - Electrically conductive polyamide resin composition - Google Patents

Abstract

PURPOSE:To provide an electrically conductive polyamide resin compsn. which is suitable for use in the production of electronics parts and has excellent moldability and impact resistance, by blending a modified ethylene copolymer having a specified composition and carbon black with a polyamide resin. CONSTITUTION:99-45wt% polyamide resin such as nylon-4 or nylon-6 is blended with 1-55wt% modified ethylene copolymer obtd. by graft-polymerizing 0.05- 1.5wt% alpha,beta-unsaturated carboxylic acid (derivative) such as acrylic acid or maleic anhydride onto a copolymer of ethylene with 3C or higher olefin such as propylene of butene-1. Then 5-90pts.wt. carbon black such as ketjen black or acetylene black is blended with 100pts.wt. above resin mixture to obtain the desired electrically conductive polyamide resin compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive polyamide resin composition. Specifically, the present invention relates to a conductive polyamide resin composition with excellent moldability.

It is known that carbon black is added to polyamide resin in order to make it conductive, but if the amount of carbon black added to improve conductivity is increased, the composition will melt. The fluidity decreases, making it difficult to perform molding processes such as injection molding, and even if molding is possible, only molded products with poor mechanical properties such as impact resistance can be obtained.

As a result of intensive research to obtain a conductive polyamide resin composition with excellent moldability, the present inventors found that when blending carbon black and a specific modified ethylene copolymer with a polyamide resin, They discovered that it was possible to obtain a molded product with greatly improved moldability and high impact resistance, and completed the present invention.

That is, the present invention aims to provide a conductive polyamide resin composition that has great industrial value.
The gist is (&) polyamide resin 99~
data weight coefficient, and (bl ethylene and α with carbon number 3 or more
- Modified ethylene copolymer obtained by graft polymerizing an α,β-unsaturated carboxylic acid or a derivative thereof to a copolymer with an olefin in θ, 0 to 50% by weight/resin mixture consisting of 10% by weight This is a conductive polyamide resin composition containing 7 parts by weight of carboaf/θ to 9θ by weight.

The present invention will be explained in detail below.

As the polyamide used in the present invention, polyamides obtained by polycondensation of lactams having three or more membered rings, polymerizable ω-amino acids, dibasic acids, diamines, and the like can be used.

Specifically, ε-caprolactam, aminocaproic acid,
Polymers such as enantholactam, 2-amine hebutanoic acid, /l-aminoundecanoic acid, teraminononanoic acid, α-pyrrolidone, α-piperidone, hexamethylene diamine, nonamethylene diamine, undecamethylene diamine, dodecamethylene diamine , a polymer obtained by polycondensing a diamine such as metaxylylene diamine with a dicarboxylic acid such as terephthalic acid, isophthalic acid, adipic acid, cepatic acid, dodecanibasic acid, or geltaric acid, or a copolymer thereof; For example, nylon, 6.7
, and //, 12.6.6.6.9.6. /θ, 6. /
/, 6.12.6T.

Examples include 6/1.6.6//2 and Otsu/6T.

Modified ethylene copolymer consists of ethylene and α having 3 or more carbon atoms.
- A copolymer with an olefin (hereinafter referred to as an unmodified ethylene copolymer) is added with an α,β-unsaturated carboxylic acid or a derivative thereof at O20
It is obtained by graft polymerization based on the weight ratio of

The unmodified ethylene copolymer that is the raw material for the above-mentioned modified ethylene copolymer can be prepared by using a Nagler-Natsuta catalyst, especially a vanadium compound such as vanadium oxytrichloride or vanadium tetrachloride, and an organoaluminum compound. molar ratio or more, preferably θ~9j molar ratio,
Jθ molti or less, preferably λθ ~ 5 molti carbon number 3
Examples include those copolymerized with the above α-olefins.

As the α-olefin having 3 or more carbon atoms, propylene,
Examples include butene-/, hexene-/, thecene-/, 9-methylbutene-/, di-methylben, and thene-1, with propylene or butene-7 being preferred.

Suitable unmodified ethylene copolymers include a series of resins sold under the Tafmer trademark by Mikata Petrochemical Industry ■, such as Tafmer A9θ♂t,
Ada θ90. Tafmer P series (ethylene-propylene copolymers) such as A2θ09θ, Tafmer PO2zaθ, Pθg♂0, Pθ6♂θ, Pθr, etc. can give.

α to be graft-polymerized to the unmodified ethylene copolymer,
Examples of β-unsaturated carboxylic acids or derivatives thereof (hereinafter simply referred to as unsaturated carboxylic acids) include acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, and anhydrides or esters of these acids. .

Among these, maleic anhydride is particularly preferred.

The amount of unsaturated carboxylic acid to be graft-polymerized to the unmodified ethylene copolymer is 0. θ
ri~/, 5-layered masugi dechiru. If this amount is too small, the effect of improving impact resistance will be small, only molded products with low tensile elongation will be obtained, and surface peeling of molded products will occur due to poor compatibility with polyamide. It's not a good size.

On the other hand, too much content is not preferable because it causes discoloration. Preferably it is in the range of 0.7 to /weight ratio.

Graft polymerization is carried out by adding unsaturated carboxylic acid to an unmodified ethylene copolymer and melt-kneading the mixture usually at 750 to 300C according to a conventional method. During this graft polymerization, α,α'-bis-t-rubberoxy-
organic peroxides such as p-diisopropylbenzene,
About θ, 0θ/ to θ, θ5 weight φ may be used for the unmodified ethylene copolymer.

The modified ethylene copolymer used in the present invention has crystallization dust (measured by X-ray method according to the description in Journal of Polymer Science, Vol.
The melt index (ASTM D/23♂
j7T) is preferably 0.0/-1θ, preferably 7< is θ, /~2θ.

In order to prepare a modified ethylene copolymer having a crystallinity and melt index as described above, an unmodified ethylene/copolymer having a crystallinity and melt index within the above ranges may be used.

The ratio of the polyamide resin and the modified ethylene copolymer is about 92 to 25% by weight of the polyamide resin, preferably 92 to 25% by weight of the modified ethylene copolymer, preferably 3% by weight of the modified ethylene copolymer, preferably about 3% by weight It is. If the amount of the modified ethylene copolymer is too small, the effects of the present invention cannot be expected. On the other hand, if it freezes in a large amount, it is not preferable because it impairs the mechanical properties such as bending strength and tensile strength of the molded product.

Carbon black is not particularly limited, but commercially available conductive carbon blacks, for example,
Ketjenblack EC (manufactured by Lion Akzo ■), Palkan X0-7j (manufactured by City Service Co., Ltd.), etc. are preferred, and in addition, hydrocarbons such as naphtha are partially oxidized in the presence of steam and oxygen to produce hydrogen and carbon monoxide. Examples include carbon black that is produced as a by-product during the production of synthesis gas containing carbon, or carbon black obtained by oxidizing it.Among these, carbon black with a specific surface area (B, E, T, low temperature nitrogen adsorption method using the formula) of 60 θm''/? Above all, especially ♂oom27y
The above is preferable, and the oil absorption amount (amount of linseed oil adsorbed to 100'l of carbon black) is λθθml
/ /p O9 or above, especially 2! Ornl/ /
002 or more is preferred.

The amount of carbon black used is 5 parts by weight per 700 parts by weight of the resin mixture of polyamide resin and modified ethylene copolymer.
It is about 0 parts by weight, preferably about 75 parts by weight. If the amount of carbon black is too small, the resulting resin composition will not have sufficient electrical conductivity. On the other hand, if there is too much, melt fluidity decreases and molding becomes difficult, and
It becomes impossible to obtain molded products with excellent mechanical properties such as impact resistance.

The polyamide resin, modified ethylene copolymer, and carbon black can be blended at any stage i up to the production of the final molded product using 10 different methods. The most common method is to mix the above three materials and knead them at temperatures of about θθ~, 2 and θC using a single screw extruder, extrude them into strands, and pelletize them, but polyamide resin and When preparing pellets made of a modified ethylene copolymer and producing a final molded product, a method of molding while adding carbon black to a molding machine can also be adopted.

The composition of the present invention can be fed to various molding machines such as extrusion, injection, compression, etc. and molded into various articles according to conventional methods, but it has excellent conductivity and impact resistance, and is light in weight. Therefore, it is particularly useful as a housing for electronic devices and electric appliances, as well as parts for automobiles and aircraft, in place of metal plates.

EXAMPLES The present invention will be specifically explained below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

In addition, "parts" in the examples indicate "parts by weight."

Production example of modified ethylene copolymer Butene with a crystallinity of 20% and a melt index of 3.6
1 content/damole ratio of ethylene-butene-7 copolymer 10
0 parts, α,α′-bis-t dissolved in a small amount of acetone
-Butylperoxy-p-diisopropylbenzene0.
0.023 parts of maleic anhydride and 0.5 parts of maleic anhydride were blended in a Henschel mixer, and the blend was
ttrm, 23θ using an extruder with L/D == 2
A modified ethylene copolymer was obtained by melt-kneading, extruding, and pelletizing at C.

After crushing a portion of the pellets, unreacted maleic anhydride was extracted with acetone, and after press molding, the amount of maleic anhydride was quantified by infrared spectroscopy, and it was found that 0.37% of maleic anhydride had undergone graft polymerization. found.

Example/Nylon-6 with a relative viscosity of 2.5 (manufactured by Mitsubishi Chemical Corporation, Tsubamitsu/θ/θ)7. s wt% and 25 wt% of the modified ethylene copolymer produced according to the above production example, a specific surface area of / / 20 Mn was added.
'/t, carbon black with oil absorption of 375 m1//θOt (manufactured by Lion Akzo ■, Ketjen Black E'
C) 23 parts were mixed and melt-kneaded using a 30 mm λ-axis extruder (manufactured by Nakatani Machinery Co., Ltd.) at a resin temperature of 2607 cm and a screw rotation speed of 7θ revolutions/min, and extrusion into pellets. Melt-kneading and extrusion were successfully performed.

The pellets thus obtained were injection molded into 3.6 oz.
Injection molding was performed at a resin temperature of 26 and a C1 mold temperature of zsC using a mold for molding an ASTM test piece. The injection pressure in this injection molding is 30
It was 0 kg/CrI.

The Izot impact strength (ASTMD2 Taro, notched l//2") of the obtained test piece was ♂, 2k.
g・cm 7cm, volume resistivity (ASTM D K
6-j%T') is! It was a battle between X10'Ω and σ.

Comparative Example/An attempt was made to mix 6,700 parts of the same nylon used in Example/ and 25 parts of carbon black and melt-knead and extrude it in the same manner as in Example/, but the melt viscosity was high and the rotation of the screw was difficult. Cross-wire extrusion could not be performed unless the speed was low, and the extrusion was made into pellets by extruding at a screw rotation speed of 20 revolutions/minute.

This pellet was injection molded in the same manner as in Example 1. The injection pressure in this injection molding is //θO
kg/cr! Met.

The Izotsu impact strength of the obtained test piece was significantly improved!・σ/
cm, and the volume resistivity was ko×10 6 Ω·α.

Sender: Mitsubishi Chemical Industries, Ltd. Representative: Patent attorney - (1 other person)

Claims (1)

[Claims] (11(a) Polyamide resin 92~/lt weight%
, and (b) a copolymer of An electrically conductive polyamide resin composition comprising 5 to 90 parts by weight of carbon black to 100 parts by weight of a resin mixture comprising 1% by weight of a modified ethylene copolymer l-tarta.