JPH0449870B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a thermoplastic resin composition containing metal powder. [Prior Art] Resin compositions containing noble metal powders are used not only as conductive resin molded products but also as conductive paints and conductive adhesives. Precious metals such as gold and silver are stable against oxidation and are preferable because they not only provide excellent conductivity as a resin composition but also maintain stable conductivity over a long period of time, but these precious metal powders are expensive and However, when used in applications such as electromagnetic wave shielding molded products and paints, the cost is high and it is difficult to put it into practical use. Therefore, attempts have been made to use inexpensive metal powders (hereinafter referred to as metal powders) such as nickel, copper, iron, and aluminum other than precious metals. For example, if a conductive resin composition is developed using copper, which is supplied in large quantities on the market at about one-hundredth of the price of silver, which is one of the cheapest precious metals, it will have practical value. is large. however,
Even when copper powder is in a resin composition, it is easily oxidized, a non-conductive oxide film is formed on the surface, and the conductivity tends to decrease over time, resulting in a product that is practically satisfactory. has not yet been reached. Generally, the surface of commercially available metal powder is covered with a non-conductive oxide film, and if it is mixed into a resin as it is, good conductivity cannot be obtained as a composition. One way to remove the oxide film on the surface of such metal powder is to wash it with an acid aqueous solution such as hydrochloric acid, but even if the metal powder obtained by this method is mixed with resin, the composition will not be as good as the manufacturing process. Although it exhibits conductivity immediately, it loses its conductivity significantly if left at room temperature for several days. [Purpose] The present inventors attempted to use a metal ion sequestering agent to modify the surface of metal powder and improve its conductivity, and discovered that a specific metal ion sequestering agent showed a unique effect. , completed the invention. [Structure] That is, according to the present invention, the general formula, (In the formula, R represents an alkyl group, a phenyl group, or an alkylphenyl group.) There is provided a conductive thermoplastic resin composition characterized by containing 0.5 to 8 parts by weight of diphosphonic acid represented by the following formula. Next, the components used in the present invention, such as the thermoplastic resin, metal powder, and diphosphonic acid, will be explained in detail. () Thermoplastic resin In the present invention, thermoplastic resins in general are used, and are appropriately selected depending on the purpose, and the type thereof is not particularly limited. For example, such things include:
Low, medium, and high density polyethylene, linear low density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, acrylonitrile-butadiene-styrene terpolymer Coalescence, polystyrene, acrylonitrile-styrene copolymer, nitrile rubber, butadiene rubber, styrene-
Butadiene rubber, ethylene-propylene-diene rubber, silicone rubber, thermoplastic polyurethane resin, polyamide resin, polyester resin, polycarbonate resin, polyvinyl chloride resin, polyacetal resin, polyphenylene sulfite resin,
Examples include modified polyphenylene oxide resin, polyetherketone resin, polyethersulfone resin, and polyetherimide resin. () Metal powder The metal powder used in the present invention is a noble metal that is not substantially oxidized, such as gold, nickel excluding silver, copper,
Powders of metals such as iron and aluminum, or alloys containing these as main components are suitable. That is, they are metal and alloy powders that form an oxide film when stored in air for a long period of time. The shape thereof does not necessarily have to be in the form of fine particles, and fibrous or flaky powders can also be used. For example, the particle size of the metal powder is usually 150 meshes or less, preferably 200 meshes or less, and fibrous powders preferably have a diameter of 100 microns or less and a length of about 5 mm or less. The content of metal powder is the amount necessary for the composition to exhibit conductivity, and is 35 to 94% by weight, preferably 50 to 93%, particularly 60 to 94% by weight, based on the total amount of resin and metal powder.
A range of 92% by weight is suitable. Generally, it is desirable to increase the content of metals with high specific gravity. On the other hand, if the amount of metal is too large, formability will be extremely reduced. () Diphosphonic acid The diphosphonic acid used in the present invention is represented by the above general formula. In the above, R is an alkyl group, a phenyl group, or an alkylphenyl group, and in this case, the alkyl group has 1 to 1 carbon atoms.
18 is common, and the alkyl in the alkylphenyl group typically has 1 to 8 carbon atoms. Examples of diphosphonic acids include 1-hydroxyethane-1,1-diphosphonic acid (hereinafter referred to as HEDP) and 1-hydroxypropane-1,1-diphosphonic acid (hereinafter referred to as HPDP).
etc. can be mentioned. The appropriate amount of diphosphonic acid to be used is 0.5 to 8 parts by weight per 100 parts by weight of the metal powder. If the amount is less than 0.5 parts by weight, the conductivity cannot be improved, and if the amount is more than 8 parts by weight, the diphosphonic acid will bleed out, which is not preferable.
Methods for adding diphosphonic acid to the composition include a method in which metal powder and diphosphonic acid are mixed in advance and then mixed with a thermoplastic resin, and a method in which a thermoplastic resin and diphosphonic acid are mixed in advance and then mixed with metal powder. , and a method of simultaneously mixing metal powder, thermoplastic resin, and diphosphonic acid is adopted. The composition according to the present invention is applied in a commonly known state and form depending on the respective purpose and use. For example, the composition of the present invention can be molded into a sheet or film using a molding means such as a calendar roll, an inflation molding machine, or a heat press in order to obtain a conductive molded product in the form of a sheet or film. be able to. In addition to the above-mentioned essential ingredients, the composition of the present invention can optionally contain conventional ingredients depending on the intended product. Furthermore, when molding the composition of the present invention,
Customary forming aids can be used. [Effects] The composition of the present invention uses diphosphonic acid in combination with metal powder, thereby exhibiting excellent conductivity without using expensive noble metals.
Moreover, conductivity is maintained for a long time. Another advantage is that the diphosphonic acid used as an additive does not bleed out. [Example] Next, the present invention will be explained with reference to an example. In addition, the conductivity in the examples is based on the Japan Rubber Association standard.
Evaluation was made using the volume resistivity value measured using SRIS2301. Bleed-out properties were comprehensively evaluated by visual judgment and gloss (JIS Z 8741) immediately after molding and after being left in a constant temperature and humidity room at a temperature of 20°C and a relative humidity of 60% for 6 months. There is no bleed-out as judged by the naked eye, and the gloss is 75% of blank.
The above items were rated as ○, those with bleed-out or gloss of less than 75% were rated as △, and those with bleed-out and gloss of less than 75% were rated as ×. The moldability of the composition was determined using a kneader with a capacity of 100 ml (Laboplast Mill manufactured by Toyo Seiki Seisakusho).
Evaluation was made using the rotor torque value when kneading the compositions in Examples at a jacket temperature of 180°C and a rotor rotation of 40 rpm. If the rotor torque value is 250 Kg-cm or less, the composition shown in the example
It can be easily press-molded into a 15 cm square plate with a thickness of 2 mm at a temperature of 150 kg/cm ² at a temperature of 150 kg/cm 2 . Example 1 5 parts by weight of different types of sequestrants were kneaded with 15 parts by weight of polypropylene and 85 parts by weight of metallic copper powder at a temperature of 180°C in a laboplast mill, and then press-molded into a 15 cm square plate with a thickness of 2 mm. did. When the conductivity and bleed-out properties of the obtained molded plate were examined, the results shown in Table 1 were obtained.

[Table] Next, 85 parts by weight of the above metal piece powder was washed with a 5% hydrochloric acid water-ethanol (1:1) solution, further washed with acetone and dried, and added to 15 parts by weight of the above polypropylene. When kneaded under the same conditions and press-molded into a plate in the same manner, the conductivity of the formed plate was examined, and the volume resistivity value immediately after forming was 7.3.
The resistance was good at ×10 ⁻² Ω−cm. After being left at room temperature for 7 days, the conductivity was significantly reduced to 2.3×10 ³ Ω-cm. Example 2 HEDP was added in different amounts to 15 parts by weight of polypropylene and 85 parts by weight of the metallic copper powder of Example 1,
The mixture was kneaded at a temperature of 180° C. in a laboplast mill, and then press-molded into a 15 cm square plate with a thickness of 2 mm. When the conductivity and HEDP bleed-out property of the obtained molded plate were measured, the results shown in Table 2 were obtained.

[Table] Example 3 Example 1 to 15 parts by weight of different thermoplastic resins
85 parts by weight of metallic copper powder, 5 parts by weight of HEDP,
The mixture was kneaded using a laboplast mill, and then press-molded into a 15 cm square plate with a thickness of 2 mm. Table 3 shows the results of the conductivity and lead-out properties of the obtained molded plate.

[Table] Example 4 The metallic copper powder of Example 1 was added to polypropylene in different amounts, and 5 parts by weight of HEDP was added to 100 parts by weight of the total amount, using Labo Plastomill. The mixture was kneaded at a temperature of 180°C, and then press-molded into a 15cm square plate with a thickness of 2mm.
The results of the conductivity and bleed-out property of the obtained molded product are shown in Table 4 together with the kneading characteristics during kneading with the Laboplast Mill. In addition, the composition of sample No. 31 had a significantly high torque value during kneading, and
It was not possible to form it into a 15cm square plate.

[Table] Example 5 A predetermined amount of different types of metal powders or metal fibers are blended into polypropylene, 3 to 5 parts by weight of HEDP is added to 100 parts by weight of the blended metals, and the mixture is kneaded using a laboplast mill. 2mm 15cm
Press-molded into a corner plate. The results of examining the conductivity and bleed-out properties of the obtained molded plate are shown below.
5.

【table】

Claims (1)

[Claims] 1. Metal powder and 100 parts by weight of the metal powder, general formula 1. An electrically conductive thermoplastic resin composition containing 0.5 to 8 parts by weight of diphosphonic acid represented by the formula (wherein R represents an alkyl group, a phenyl group, or an alkylphenyl group).