JPH04153257A - Conductive polycarbonate resin composition - Google Patents

Abstract

PURPOSE:To obtain a conductive polycarbonate resin composition having conductivity and dimensional accuracy desirable for precision electronic components, etc., by mixing a thermoplastic aromatic polycarbonate with a specified high- density poly ethylene, glass fibers, carbon fibers, carbon black and a melamine/ cyanuric acid adduct. CONSTITUTION:An antistatic polycarbonate resin composition is prepared by mixing 30-86 pts.wt. aromatic polycarbonate (A) with 2-15 pts.wt. high-density polyethylene (B) of a density of 0.945-0.97g/cm<3> and a melt flow rate of 0.1-30g/10min), 5-20 pts.wt. glass fibers (C) (of a mean diameter of 3-15mum and a mean length of 0.05-10mm), 5-20 pts.wt. carbon fibers (D) (of a mean diameter of 3-20mum and a mean length of 0.03-15mm), 2-15 pts.wt. conductive carbon black (E) and 0.01-5 pts.wt., per 100 pts.wt. in total of A-E, melamine/cyanuric acid adduct (F) (of a mean diameter of 0.1-50mum).

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention has electrical conductivity and dimensional accuracy suitable for precision electronic parts, etc., and also has stability against single boundary temperature changes, oil resistance, and mechanical properties. The present invention relates to a resin composition that has excellent mechanical strength and dramatically improved moldability, etc.

(Prior Art) The bases for mounting parts of electronics of household appliances, video equipment, etc. are rapidly becoming lighter, thinner, and have more diverse specifications.

For example, the base on which video parts (peripheral parts for magnetic tape running, etc.) are installed has electrical conductivity to prevent noise, and
Dimensional accuracy and stability 1 Strong mechanical properties and oil resistance are required.

Conventionally, aluminum alloys have generally been used as materials in this field.

(Problems to be Solved by the Invention) However, aluminum alloys have disadvantages in that they are heavy, have poor productivity, and require various secondary processes, resulting in high costs.

For this reason, there has been a strong demand in the market for thermoplastic resins that are lightweight, have excellent productivity, and can reduce costs.However, composite materials that are improved from conventional thermoplastic resins do not meet these various required properties. Therefore, it is difficult to replace metal parts, and for example, composite materials using polybutylene lenticulate resin have the disadvantage of insufficient oil resistance, making them impractical. .

An object of the present invention is to provide a composition that solves the above problems.

(Means for Solving the Problems) The conductive polycarbonate resin composition of the present invention is characterized by comprising the following components (a) to (f).

(a) 30 to 86 parts by weight of thermoplastic aromatic polycarbonate (b) Density is 0.945 to 0.970 g/c+n'' and melt flow rate is 0.1 to 30 g/10
2 to 15 parts by weight of high-density polyethylene (C) 5 to 20 parts by weight of glass fibers with an average diameter of 3 to 151711 and an average length of 0.05-10+on (d) Average diameter of 3 to 20F , and the average length is 0.
03-15 mm carbon fiber 5-20 parts by weight (e) Conductive carbon black 2-15 parts by weight (f) Melamine/cyanuric acid adduct with an average diameter of 0.1-50 mm The above components (a), (b) ), (c), (d) and (e) in a total amount of 0.01 to 5 parts by weight based on 100 parts by weight of the total amount of the thermoplastic aromatic polycarbonate used in the present invention. It consists of a moiety having two phenolic hydroxyl groups, or a modified product thereof. Specific examples of such dihydric phenols include bisphenols, of which bisphenol A is preferred.

Aromatic polycarbonates are produced by reacting the above-mentioned dihydric phenols with carbonate precursors such as phosgene, bischloroformates, carbonic diesters, etc., but an appropriate one can be selected from commercially available products. can be obtained.

Examples of the modified product include a blend of polycarbonate with an acrylonitrile-butadiene-styrene terpolymer resin, a polycarbonate pellet impregnated with a styrene monomer, and polymerized.

The high density polyethylene used in the present invention has a density of 0.94
5-0. It is a high-density polyethylene with a density of 970 g/cm'', and if it is outside this range, good conductivity cannot be obtained.

In addition, the melt flow rate (MFR), which is a guideline for the fluidity of this polyethylene, is 0.1 to 30 g/10 minutes at 190°C and a load of 2.16 kg, preferably 0.5 to 15 g/10 minutes. It's worth it. If the MFR is less than this range, the conductivity of the resin composition will be poor, and if it is too high, the appearance will be poor.

The glass fibers used in the present invention have an average diameter of 3 to 15 Jj.
11 can be applied, preferably 5 to 12F,
The average length is 0.05 to 10 mm, preferably 0.1 to 6 mm.
It belongs to m. If the average diameter is outside this range, sufficient mechanical strength of the resin composition cannot be obtained, and if the average length is outside this range, sufficient dimensional accuracy cannot be obtained.

By using such glass fibers, for example, in the molded product after being subjected to injection molding, the glass fibers are somewhat shortened and dispersed with an average length of 0.05 to 10 mm.
The effects of the invention will be best achieved.

The glass fiber may contain a surface treatment component for the purpose of adhesion and affinity with the above-mentioned thermoplastic aromatic polycarbonate, and the adhesion amount is generally about 0.01 to 0.6% by weight. It is.

This glass fiber can be appropriately selected from commercially available products, but when manufacturing it, for example, 1.
Marble (glass beads of a predetermined size) is heated and softened in a furnace table, and is flowed down from a number of nozzles on the furnace table.While this base material is stretched at high speed, a sizing agent is applied by dipping in a sizing agent applicator. It is manufactured by focusing, drying, and winding on a rotating drum. At this time, the average diameter of the glass fibers is determined by selecting the nozzle diameter and drawing conditions.

The glass fiber may be in any form such as roving, chopped strand, or strand, and may also be a so-called milled fiber or a crushed product of strands called glass powder, but chopped strands may be used in view of ease of mixing with resin. The composition of the raw material glass is preferably alkali-free, and one example is E glass.

The carbon fiber used in the present invention is a general chopped carbon fiber, but when high mechanical properties and dimensional properties are required as in the composition of the present invention, a PAN (polyacrylonitrile) method is used. Manufactured products are preferred.

The average diameter of this fiber is 3-20P, preferably 3-10P.
P, and the average length is 0.03 to 15 mm, preferably 0.
It is 5 to 10 mm. If it is outside this range, the mechanical strength and dimensional accuracy of the resin composition will decrease, which is not preferable.

In addition, by using such carbon fibers, which preferably have a carbon composition of 95% or more, the average length of the molded article after being subjected to injection molding becomes somewhat shorter, for example, 0.03 to 0.03%. 15mm, preferably 0.03-5m
m of carbon fibers, resulting in a good balance of mechanical properties and dimensional properties.

This material may contain a surface treatment component for the purpose of adhesion and affinity with the thermoplastic aromatic polycarbonate, and the amount of the component attached is generally about 2 to 8% by weight.

As the conductive carbon black used in the present invention, in addition to highly conductive acetylene black and oil furnace black, thermal black and channel black, which have low conductivity but can achieve satisfactory conductivity when used in a large amount, are suitable.

It is desirable that this carbon black can impart the necessary conductivity to the composition with a small amount of addition, so acetylene black and oil furnace black, especially oil furnace black, have fewer impurities and have excellent conductivity. Therefore, it is preferable, but especially X ()”
(Extra Conductive Furnace
Black), SCF (SuperCond
uctive Furnace Black), C
F (Conductive Furnace Black
k) and S A F (Super Abrasion
Furnace Black) can be preferably used. Among them, the BET formula specific surface area due to N adsorption is 850m"7g
XC
Examples of F include Ketsch-En-Black ECJ (trade name) by Ketsch-En-Black International, Palcan XC-72J (trade name) by Cabot, etc.
Examples of CF include Cabot's Palcan SCJ (trade name) and Palcan PJ (trade name), Degussa's Corax LJ (trade name), etc.; , Columbia's [Conductex SCJ (trade name)]
etc., and SAF also has Asahi Carbon Co., Ltd.'s “Asahi #
9" (trade name), Mitsubishi Chemical Industries, Ltd.'s Diamond Black AJ (trade name), Capot's "Palcan 9"
(trade name) etc. These may be used in combination.

Normally, when polycarbonate and high-density polyethylene are blended, delamination (layer separation phenomenon) occurs due to lack of compatibility, but highly conductive oil furnaces have a surface layer rich in graphite structure, and this special carbon black surface The graphite structure exhibits a specific affinity with the crystal structure of high-density polyethylene and is extremely compatible with the crystal structure of high-density polyethylene, resulting in a unique compatible structure that does not cause delamination and exhibits high conductivity. This is preferable because the effects of the invention are brought out even more markedly.

The melamine/cyanuric acid adduct used in the present invention can be obtained, for example, by a method of reacting melamine with cyanuric acid or incyanuric acid in an aqueous medium. Among them, the preferred one is
This is a surface-treated melamine/cyanuric acid adduct obtained by using, as the aqueous medium, an organic solvent and a surface treatment agent for the melamine/cyanuric acid adduct substantially uniformly dissolved therein. As such a manufacturing method, for example, the method proposed in Japanese Patent Application No. 1-260849 can be adopted.

As the surface treatment agent for the melamine-cyanuric acid adduct, since the surface treatment agent largely depends on the resin component in which the melamine-cyanuric acid adduct is blended, polymers similar to the resin component are generally preferred. As long as the surface-treated melamine/cyanuric acid adduct has good compatibility with the resin component and can be uniformly dispersed, it is not necessarily limited to those similar to the resin component.

In the present invention, a melamine/cyanuric acid adduct surface-treated with polycarbonate is particularly preferred.

There are no particular restrictions on the concentration of the surface treatment agent in the organic solvent, as long as it is soluble in the organic solvent and can form a thin and homogeneous film of the surface treatment agent on the surface of the melamine/cyanuric acid adduct. However, it is preferably 1 to 50% by weight.

This reaction is usually carried out under normal pressure, and the reaction temperature varies depending on the type of solvent used, but the reaction rate is slow at normal temperature.
Most preferred is the boiling point of the solvent.

The reaction time cannot be absolutely determined depending on the reaction temperature, but for example, when the reaction temperature is 50 to 60°C, it is about 2 hours, 8 hours.
In the case of 0 to 90°C, it is about 1 hour.

The thickness of the coating of the surface treatment agent formed on the surface of the melamine/cyanuric acid adduct is preferably 0.001 to 0.5 -.

The average particle diameter of the melamine/cyanuric acid adduct used in the present invention is O, 1 to 50P, preferably 05 to 30F.
If the average particle diameter is less than the lower limit of the above range, the dispersibility in the resin component may deteriorate, and if it exceeds the upper limit of the above range, the dimensional accuracy of the resulting composition may deteriorate. The improvement effect may be smaller.

The blending amounts of these components used in the present invention are (a) 30 to 86 parts by weight of thermoplastic aromatic polycarbonate, preferably 35 to 70 parts by weight, and (b) 2 parts by weight of high-strength polyethylene.
~15 parts by weight, preferably 2 to 10 parts by weight, (C) 5 to 20 parts by weight, preferably 5 to 1 part by weight of glass fiber
5 parts by weight, (d) 5 to 20 parts by weight of carbon fiber, preferably 5 to 15 parts by weight.
parts by weight, (e) 2 to 15 parts by weight, preferably 2 to 10 parts by weight of conductive carbon black, (f) melamine/cyanuric acid adduct as the aforementioned components (a), (b), (c), (d) and (e)
The amount is 0.01 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the total amount.

A composition in which the blending amount of the thermoplastic aromatic polycarbonate is outside the above range cannot achieve the object of the present invention.

If the amount of high-density polyethylene is less than the lower limit of the above range, the conductivity, oil resistance and impact resistance of the composition will be poor, and if it exceeds the upper limit of the above range, the composition will have poor bending strength. and poor impact resistance.

If the amount of glass fiber blended is less than the lower limit of the above range, the bending strength and dimensional stability of the composition will be poor, and if it exceeds the upper limit of the above range, the moldability and conductivity of the composition will be poor. Inferior.

If the amount of carbon fiber blended is less than the lower limit of the above range, the composition will have poor bending strength and impact resistance, as well as poor conductivity and dimensional stability; if it exceeds the upper limit of the above range, , the moldability of the composition is poor.

If the amount of carbon black is less than the lower limit of the above range, the conductivity of the composition will be poor, and if it exceeds the upper limit of the above range, the composition will have poor impact resistance.

If the blending amount of the melamine/cyanuric acid adduct is less than the lower limit of the above range, the composition will not be effective in molding processability, and if it exceeds the upper limit of the above range, the composition will not be processed properly. target strength is poor.

The composition of the present invention may contain additional components in addition to the above-mentioned components within a range that does not significantly impair the effects of the invention.

Additional ingredients include various fillers other than the above ingredients, such as:
Calcium carbonate (heavy, light, colloid), talc, mica, silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, zinc oxide, zeolite, tulastonite, diatomaceous earth, glass peas, bentonite, montmorillonite , asbestos, hollow glass bulbs, graphite, molybdenum disulfide, titanium oxide, aluminum fibers, stainless steel fibers, brass fibers, aluminum powder, wood flour, rice husks, etc.: thermoplastic resins, such as polypropylene, the above essential component (b) polyethylene, polyamide, polyethylene terephthalate, polybutylene terephthalate, propylene-ethylene block or random copolymers, maleic anhydride-modified polyolefins, rubber or latex components such as ethylene-propylene copolymer rubber, styrene-butadiene rubber, styrene-butadiene - Styrene block copolymers or hydrogenated derivatives thereof, polybutadiene, polyisobutylene, etc.: thermosetting resins, such as epoxy resins, melamine resins, phenolic resins.

Unsaturated polyester resin, etc.: Antioxidants (phenolic, sulfur, phosphorus, amine, etc.): Lubricants: Various organic and inorganic pigments: Ultraviolet absorbers: Antistatic agents; Dispersants: Neutralizing agents: Foaming Agents: plasticizers: copper damage inhibitors: Ii retardants: crosslinking agents: flowability improvers.

The addition of these additional ingredients improves the physical property balance, molded product surface characteristics (surface scratch resistance, gloss, weld appearance, silver streaks, flow marks, etc.), printability, paintability, adhesion, plating performance, moldability, It is effective in improving durability, etc.

The composition of the present invention can be produced using a conventional mixing machine such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll, a Brabender plastograph, or a kneader.

:A Usually, the above essential components and optional additional components are kneaded in an extruder or the like to form a pellet-like compound and then subjected to processing, but in special cases, each component is directly fed to a molding machine, It is also possible to mold the composition while kneading it. Alternatively, the above-mentioned (b) to (f) components are mixed in advance at a high concentration to form a masterbatch, and then blended and compounded while diluting with the above-mentioned (a) component and other components, or directly molded. You can also do that.

Further, the composition of the present invention can be molded using a conventional molding machine for thermoplastic resins. That is, it can be applied to injection molding, extrusion molding, blow molding, thermoforming, etc.

In the composition of the present invention obtained in this way, the dispersed domains of high-density polyethylene do not exist in the state of independent particles in the aromatic polycarbonate (a) matrix, but form a continuous circuit in the form of a network. In addition to the unique structure in which most or substantially all of the carbon black is contained in this circuit, the continuous circuits are further connected by carbon fibers, forming a dense conductive network. is forming.

In addition to this, glass fibers are uniformly dispersed together with carbon fibers, and in particular, in molded bodies molded under high shear rates such as injection molding, the dispersion of these fiber components has been Contrary to common sense, it has the characteristic that there is not much directionality and the dispersion is q.

(Effects of the Invention) The composition of the present invention has excellent conductivity and dimensional accuracy by uniformly and selectively controlling the dispersion of a specific conductive filler and reinforcing fibrous filler without directionality. These effects include excellent stability, mechanical strength, and oil resistance.

In particular, when producing various parts by injection molding, the composition of the present invention has extremely excellent molding processability, so it can be molded at low injection pressure, and when molding is performed using a mold with a complex shape. , there is little unevenness in filling the material into the mold (a uniform structure can be obtained).

Furthermore, the composition of the present invention can be used as a substitute for metal parts, which conventional thermoplastic resins could not be used for, and can also be applied to conductive precision electronic parts.

(Example) Examples 1 to 4 and Comparative Examples 1 to 6 Polycarbonate, high density polyethylene (density 0.95
0, MFR5.2g/10min), glass fiber with an average diameter of 10F11 and an average length of 1.5+a+s, carbon fiber with an average diameter of 9μ and an average length of 6mm (PAN method), specific surface area 900m
After mixing 7 g of oil furnace carbon black (Ketchen Black ECJ (trade name) manufactured by Akzo) and the melamine/cyanuric acid adduct prepared as shown below in the proportions shown in Table 1, The mixture was kneaded using a pressing machine to form pellets.

9.82 g of melamine, 100.6 g of incyanuric acid (molar ratio 1:1), and 28.5 g of polycarbonate were placed in a four-bottle flask equipped with a cooling tube and a stirrer, and then 2000 g of tetrafluorofuran and 22 g of water were added.
After adding 2 g of the mixed solvent, the mixture was heated while stirring. After the temperature inside the system reached 62°C in about 1 hour, the reaction was further aged for 1 hour and 30 minutes at the same temperature.Next, the solvent was separated from the obtained reaction solution by furnace, and the reaction was heated at 50°C. After drying for 5 hours, this was crushed to obtain a melamine/cyanuric acid adduct surface-treated with polycarbonate. In addition, apart from this, in the above reaction, the same reaction was performed except that bocarbonate and tetrafluorofuran were removed,
A melamine/cyanuric acid adduct without surface treatment was also synthesized. In Table 1, it is represented by component (f).

Next, test pieces were molded from the obtained pellets using a screw in-line injection molding machine, and the following physical properties were tested and evaluated.

The results are shown in Table 1.

(1) Volume specific resistance value Compliant with Japan Rubber Association 5RIS2301.

(2) Surface resistance value It was measured using a Loresta surface resistance meter manufactured by Mitsubishi Yuka Co., Ltd.

(3) Izotsu impact strength Compliant with ASTM D256.

(4) Bending strength Compliant with ASTM D790.

(5) Oil resistance The specimen shown in Fig. 1 (length 20 mwr, width 4 oram, thickness 1.8 mm) was molded by injection molding, and its protrusion a (outer diameter 4 mm, inner diameter 1.477 mm, height 2 After dropping oil "Diamond RO32J (trade name)" into a hole of .5m5), press a bottle with a diameter of 1.48m+■ into the hole and heat it to 80℃.
The sample was left in an oven for 24 hours, and the presence or absence of cracks in the protrusion was evaluated.

(6) Dimensional accuracy The specimen shown in Figure 2 (height: 80 mm, width: 120 mm, thickness: 2 m)
m) was manufactured by injection molding, and after it was left at a specified temperature for 24 hours, the shrinkage rate in the resin flow direction (vertical direction) was determined between the mold dimension marks (+ marks) on the specimen surface. .

(7) Injection molding pressure The injection pressure when producing the specimen shown in FIG. 2 was determined.

4,

[Brief explanation of drawings]

FIG. 1 is a perspective view of an oil resistance evaluation specimen. Figure 2 shows FIG. Ru. No. figure

Claims (1)

[Scope of Claims] A conductive polycarbonate resin composition comprising the following components (a) to (f). (a) Thermoplastic aromatic polycarbonate 30-86 parts by weight (b) High-density polyethylene 2 having a density of 0.945-0.970 g/cm^3 and a melt flow rate of 0.1-30 g/10 min ~15 parts by weight (c) The average diameter is 3 to 15 μm and the average length is 0
．． 5 to 20 parts by weight of glass fibers of 0.05 to 10 mm (d) having an average diameter of 3 to 20 μm and an average length of 0
．． 5 to 20 parts by weight of carbon fibers having a diameter of 3 to 15 mm (e) 2 to 15 parts by weight of conductive carbon black (f) Melamine/cyanuric acid adduct having an average diameter of 0.1 to 50 μm The above components (a) and (b) , 0.01 to 5 parts by weight per 100 parts by weight of the total amount of (c), (d) and (e).