JPH0348219B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is capable of producing a low melting point metal by kneading a resin and a low melting point metal or alloy at a temperature higher than the melting point or solidus temperature of the latter, and mixing and dispersing the metal or alloy in the resin. or a thermoplastic resin composition containing fibers of an alloy (hereinafter simply referred to as a low melting point metal), specifically a thermoplastic resin composition containing 10 to 1000 parts by weight of a low melting point metal fiberized to 100 parts by weight of a thermoplastic resin. This relates to a manufacturing method. [Problems to be solved by conventional technology and inventions] With the rapid spread of electronic devices in recent years, electromagnetic shielding materials that prevent electromagnetic waves emitted by these devices and conductive materials that add conductivity to synthetic resins as materials for electronic devices have attracted attention. and many proposals have been made. BACKGROUND ART Conventionally, as a method of imparting a high degree of conductivity to a synthetic resin, there is a method of mixing a fibrous metal with a high melting point into the synthetic resin. In this method, pre-fiberized high melting point metal fibers and thermoplastic resin are thoroughly kneaded using an extruder, mixer, etc., and then molded into a predetermined shape using an extruder. In order to provide a high degree of conductivity, it is necessary for the metal fibers to be in sufficient contact with each other in the synthetic resin, and for this purpose, it is preferable that the ratio of the length to diameter of the metal fibers, that is, the aspect ratio, be large. With conventional methods, it has been extremely difficult to economically obtain metal fibers with such a large aspect ratio, ie, large length and small diameter, due to productivity constraints. Furthermore, it is difficult to uniformly mix a large amount of fibers with a large fiber length with a synthetic resin, and it requires a great deal of time and power. Moreover, it reduces the aspect ratio of metal fibers cut during kneading,
Alternatively, it is difficult to obtain a sufficient conductive effect due to non-uniform mixing. Furthermore, when these mixtures are extruded or injection molded, the apparent viscosity of the mixture becomes extremely high because solid metal fibers are mixed in, resulting in poor moldability and the need for a large amount of power, resulting in low productivity. . [Means for Solving the Problems] The present invention eliminates the drawbacks of these conventional techniques and provides an industrially advantageous production method of a highly conductive metal fiber-containing thermoplastic resin composition based on a completely new idea. The present invention provides a method. That is, the gist of the present invention is that thermoplastic resin 100
A mixture of 10 to 1000 parts by weight of a low melting point metal or alloy is kneaded using an extruder or mixing roll at a temperature higher than the melting point of the metal or the solidus temperature of the alloy, and then mixed with a resin molding machine. Method for producing a thermoplastic resin composition containing metal fibers, characterized in that the composition is drawn at a temperature higher than the melting point of the metal or the solidus temperature of the alloy and higher than the forming linear velocity, and 100 weight of thermoplastic resin For the department,
A mixture containing 10 to 1000 parts by weight of a low melting point metal or alloy is kneaded using an extruder, mixing roll, or mixer at a temperature higher than the melting point of the metal or the solidus temperature of the alloy, and then subjected to a pelletizing or sheeting process. , a thermoplastic resin composition containing metal fibers, which is taken by a resin molding machine at a temperature higher than the melting point of the metal or the solidus temperature of the alloy, and at a speed higher than the molding linear speed. It depends on the manufacturing method. [Function] Unlike the conventional technique of mixing synthetic resin and ready-made metal fibers, the method of the present invention utilizes the fluidity of the synthetic resin to mix the synthetic resin and unfiberized metal during molding. It turns metal into fibers. This is represented by the following flow sheets 1 and 2 in process diagrams.

[Examples and effects of the invention]

The content of the present invention will be explained in more detail with reference to Examples below. Hereinafter, parts simply mean parts by weight. Example 1 Polystyrene resin Denka Styrol HRM-2
(Manufactured by Denki Kagaku Co., Ltd.) 70 parts impact-resistant polystyrene resin S-Bright 500A
(manufactured by Showa Denko) 25 parts impact-resistant polystyrene Toughprene 691 (manufactured by Asahi Kasei) 5 parts zinc-tin alloy (zinc 8%, melting point 200°C) 150 parts zinc stearate 1 part at 220°C in a Brabender plastograph, 5 parts After kneading for a minute, the mixture was made into pellets and extruded into rods using a 20 mmφ extruder (L/D=20). At the time of take-off, the take-off speed was 15 times the extrusion line speed. The obtained rod-shaped product was cut into pieces of 1 cm in length and molded using an injection molding machine for making dumbbell-shaped samples at a resin temperature of 190°C and a mold temperature of 70°C. When the resulting molded product was treated with toluene to dissolve the resin, most of the metal was found to be delicately fibrous, with a thickness of 3μ to 80μ. Example 2 Low density polyethylene resin Petrocene 208 (MI=23)
(Toyo Soda Kogyo Corporation) 70 parts Low density polyethylene resin Mirason FL-60 (MI=
70) (manufactured by Mitsui Polychemical Co., Ltd.) 30 parts of low melting point alloy U-Alloy 150A (melting point 150°C, manufactured by Osaka Asahi Metal Co., Ltd.) 150 parts were heated to 180°C in a 40 mmφ extruder (L/D = 30, tip Dalmage type screw) It was extruded into a rod shape at a screw rotation speed of 100 rpm. The extrudate was cooled to such an extent that it would not break when it was taken off, and the extrudate was taken off at high speed (40 m/min). Cut the obtained 2 mm thick stick into 5 mm length.
The material was placed in an injection molding machine with a box-shaped mold, and injection molded at a resin temperature of 140°C and a mold temperature of 70°C. When the resin of the obtained molded product was melted in decalin at 100℃, the low melting point alloy was in the form of delicate fibers with a size of 3μ to 70μ, so it was found that the low melting point metal was fibrous in the resin of the injection molded product. It was confirmed that it contained a large amount. Example 3 In the formulation of Example 1, 300 parts of lead-bismuth alloy (30% bismuth) was used instead of zinc-tin alloy,
A molded article was obtained in the same manner as in Example 1, except that extrusion was carried out at 220°C and injection molding was carried out at 180°C. When I measured the electrical resistivity of this thing, it was 0.2.
It was Ω・cm.

Claims (1)

[Scope of Claims] 1. A mixture of 10 to 1000 parts by weight of a low melting point metal or alloy is blended with 100 parts by weight of a thermoplastic resin and heated to a temperature higher than the melting point of the metal or the solidus temperature of the alloy using an extruder or mixing roll. A thermoplastic resin containing metal fibers, which is kneaded at a temperature and taken by a resin molding machine at a temperature higher than the melting point of the metal or the solidus temperature of the alloy and at a speed higher than the forming linear speed. Method for producing the composition. 2 A mixture of 10 to 1000 parts by weight of a low melting point metal or alloy is mixed with 100 parts by weight of a thermoplastic resin and kneaded at a temperature higher than the melting point of the metal or the solidus temperature of the alloy using an extruder, mixing roll or mixer. , a metal characterized in that, after undergoing a pelletizing or sheeting step, it is taken by a resin molding machine at a temperature higher than the melting point of the metal or the solidus temperature of the alloy, and at a speed higher than the linear forming speed. A method for producing a thermoplastic resin composition containing fibers.