JPH01284553A - Conductive resin composition - Google Patents

Abstract

PURPOSE:To obtain a conductive resin composition having improved mechanical properties and conductivity by mixing a polyamide resin with a metallic fiber and a specified acrylic modifier. CONSTITUTION:100 pts.wt. polyamide resin is mixed with 15-300 pts.wt. metallic fiber (e.g., brass fiber) and 5-80 pts.wt. acrylic modifier comprising a polyphase amine-reactive prepolymer comprising 50-90wt.% phase of an acrylic elastomer obtained by polymerizing a (1-15 C) alkyl acrylate with a (substituted) butadiene, other ethylenically unsaturated monomers, a polyethylenically unsaturated crosslinking monomer and a graft-bonding monomer and a phase of a polymer obtained by polymerizing a monomer having an amine-reactive functional group (e.g., acrylic acid).

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a conductive resin composition.

More specifically, the present invention relates to a conductive resin composition that has excellent mechanical properties and electrical conductivity and is suitable for electrical and electronic components, electronic device casings, and automobile parts.

(Problems to be Solved by the Prior Art and the Invention) With the recent rapid development of electronics, the problem of countermeasures against electromagnetic interference has been greatly amplified.

This means that the main parts such as the housing of electronic devices are made of resin,
This is because unnecessary electromagnetic waves emitted from ICs, LSIs, etc. are transmitted through the device, increasing the chances that electronic devices will cause interference to each other. As a countermeasure against this problem, a method of forming a conductive layer on the surface of a resin molded product has conventionally been used, but this method has drawbacks such as an increase in the number of steps and peeling of the conductive layer. For this reason, composite resins in which resins are filled with conductive fillers have recently attracted attention. For example, JP-A-59-202257 describes that a conductive polyamide resin made of metal fibers, a polyamide resin, and an ionomer resin has excellent impact resistance and conductivity.

By the way, when metal fibers are composited with a resin that has impact resistance in order to impart conductivity, the shock wave applied to the notch part of the notched Izotz test piece propagates through the metal fibers in the resin, resulting in a decrease in impact resistance. There is a drawback that it does. In addition, if non-conductive glass fiber is used as a reinforcing material to improve the impact resistance, it is necessary to add metal fiber to maintain the conductivity of the composition, which increases the cost. It has the disadvantages of poor amplifier performance, poor workability, and increased specific gravity. When conductive carbon fiber is used as a reinforcing material, the composition has disadvantages of increased cost and poor processability.

Furthermore, in order to further improve the impact resistance of filler-free resins, a method of blending a rubber component has been used, but a decrease in rigidity and heat distortion temperature is unavoidable. When metal fibers are blended into such polymer alloys, the rigidity and heat distortion temperature are improved, but there is a drawback that the impact resistance performance is significantly reduced.

The present inventors completed the present invention as a result of intensive research to solve the above-mentioned problems. An object of the present invention is to provide a conductive resin composition with excellent mechanical properties and electrical conductivity.

(Means for Solving the Problems) That is, the conductive resin composition of the present invention consists of a polyamide resin 1
00 parts by weight, 15 to 300 parts by weight of +Bl metal fibers and 5 to 80 parts by weight of (C) acrylic modifier are blended, and the acrylic modifier (Q is acrylic elastomer It is characterized by being a multi-phase amine-reactive moiety-containing polymer consisting of a coalesced phase [1] and a polymer phase [2] containing a functional group that is reactive with amines.

The present invention will be explained in detail below.

The polyamide resin used in the present invention is not particularly limited as long as it is a known polyamide. Examples of suitable polyamide resins include polyamides made from polymerizable monoaminomonocarboxylic acids or their amide-forming derivatives, or from suitable diamines and suitable dicarboxylic acids or from their amide-forming derivatives, such as nylon. 4゜Nylon 6, Nylon 7, Nylon 8. Nylon 11, nylon 12. nylon 66, nylon 69,
Nylon 610. Nylon 611. Nylon 612. Examples include homopolymers such as nylon 6T, mixtures of two or more thereof, and copolymers.

The metal fibers used in the present invention include brass fibers, iron fibers, aluminum fibers, etc., with brass fibers and iron fibers being particularly preferred.

It is important that the amount of metal fiber used in the present invention is 15 to 300 parts by weight, particularly preferably 25 to 100 parts by weight, based on 100 parts by weight of the polyamide resin. When the amount of metal fibers is less than 15 parts by weight, the effect of imparting conductivity is insufficient. On the other hand, 300
If the weight part is reduced, fluidity decreases, making molding by injection molding extremely difficult.

The acrylic modifier (C) used in the present invention consists of an acrylic elastomeric polymer phase [1] and a polymer phase [2] containing a functional group reactive with amines. Polymers containing multiphase amine-reactive moieties include, for example, those disclosed in JP-A No. 47-6284. Among them, acrylic elastomeric polymers obtained by polymerizing monomers consisting of alkyl acrylates, butadiene, substituted butadiene, other ethylenically unsaturated monomers, polyethylenically unsaturated crosslinking monomers, and graft bonding monomers. Preferably, it consists of 50 to 90 sanji*4 layers of 8 yen (more preferably 50 to 90 sanji*4 %). The alkyl acrylate monomer of the acrylic elastomeric polymer has an alkyl group having 1 to 15 carbon atoms, preferably 1 to 8 carbon atoms. In addition, other ethylenically unsaturated monomers include styrene,
α-methylstyrene, vinyl halonide, amide,
Examples include esters.

A polyethylenically unsaturated crosslinking monomer has a plurality of unsaturated groups capable of addition polymerization, all of which are mutually,
Further, it participates in the polymerization reaction at approximately the same rate as the first monomer, the alkyl acrylate monomer, other acrylic monomers, and other reactive monomers. These include polyacrylic esters and polymethacrylic esters of polyols, such as butylene diacrylate, butylene dimethacrylate, vinyl acrylate, vinyl methacrylate, and the like.

Grafting monomers are monomers having two or more addition-polymerizable unsaturated reactive groups that participate in the polymerization reaction at substantially different rates. The monomer may be such that at least one reactive group polymerizes at about the same rate as the other monomers, or at a slightly lower rate, and the remaining groups polymerize at a substantially different rate, e.g., a relatively slower rate. preferable.

These include acrylic acid, methacrylic acid, maleic acid (mono and diesters), allyl methacrylate, allyl acrylate. Examples of the substituted butadiene include isoprene, chloroprene, and siatubucdiene.

On the other hand, a polymer containing a functional group reactive with an amine is a polymer obtained by copolymerizing a monomer having a functional group reactive with an amine. Examples of monomers that can be copolymerized and have a functional group that reacts with amines include acrylic acid and methacrylic acid.

Examples include carboxylic acids such as fumaric acid, maleic acid, α-hydroquine methylacrylic acid, and adipic acid. Also,
Other monomers include alkyl methacrylates, styrene, α-methylstyrene, methacrylic esters, and the like.

The elastomeric polymer phase and the polymer phase containing functional groups reactive with amines must be chemically bonded. As such an acrylic modifier, for example, the product name [Balaroid EX] manufactured by Rohm and Haas Co., Ltd.
The one commercially available as L-3386J is preferred.

In the present invention, it is important that the amount of the acrylic modifier is 5 to 80 parts by weight, particularly preferably 10 to 60 parts by weight, based on 100 parts by weight of the polyamide resin. If the amount of the acrylic modifier is less than 5 parts by weight, the impact resistance will be insufficient.

On the other hand, if it exceeds 80 parts by weight, fluidity decreases and molding by injection molding becomes extremely difficult.

The composition of the present invention further includes a coloring agent, if necessary.

A heat stabilizer, a lubricant, a crystal nucleating agent, etc. can be added.

It is important that the composition of the present invention has a sufficient crosstalk fraction before it becomes a final molded product. As a method for this purpose, for example, there is a method of making a pellet-shaped resin using a twin-screw kneading extruder rotating in opposite directions and subjecting it to a molding process.

(Effects of the Invention) The conductive resin composition of the present invention has excellent mechanical properties and conductivity, and is suitable for electrical and electronic components, electronic device casings, and automobile parts.

(Example) The present invention will be specifically explained below using Examples.

The physical properties were evaluated according to the following method.

], Tensile strength: ASTM I)-6382, Modulus of elasticity: ASTM D-7903, Izot impact strength (1/4 inch, notched): ASTM D-2
56 4. Heat distortion temperature (18.6kg/cm”): ASTM
D-648 5, Volume resistivity: ASTM I)-257 Example 1
~6. Comparative Examples 1 to 4 Steel fiber (■Kobe Cast Iron Shinsei EXL-3386) was added to 100 parts by weight of nylon 6 resin (Kanebo ■MC-1O2).
) were blended with the composition shown in Table 1 and pelletized using a 30 mm diameter twin-shaft, counter-rotating kneading extruder.

The obtained pellet was molded into a test piece using an injection molding machine, and the physical properties of the test piece were evaluated. The results are shown in Table-1.

Example 7. Comparative Examples 5 to 7 Nylon 66 resin (Amiran 3001-N manufactured by Toshi ■)
To 100 parts by weight, 60 parts by weight of brass fiber (KC-Metal Fiber C-2600 manufactured by A11 Kobe Cast Iron Works) and 40 parts by weight of the volume impact modifier shown in Table 2 were blended.
Ballen 1 was prepared using a 0 mm diameter two-axis, counter-rotating kneading extruder.
It became ~. Next, the conductive resin composition according to the present invention was molded into a test piece, and the physical properties of the test piece were evaluated in the row IO. It is a conductive resin composition.

Procedural amendment

Claims (1)

[Scope of Claims] (B) 15 to 300 parts by weight of metal fibers and (C) 5 to 80 parts by weight of an acrylic modifier are blended with 100 parts by weight of (A) a polyamide resin, the acrylic A multiphase amine-reactive moiety-containing polymer in which the system modifier (C) is composed of an acrylic elastomeric polymer phase [1] and a polymer phase [2] containing a functional group that is reactive with amines. A conductive resin composition characterized by: