JPH0553604B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a thermoplastic resin composition containing chopped conductive fiber strands having electrical conductivity. [Prior art] Thermoplastic resins are lightweight, moldable, heat resistant, and have good electrical insulation properties, so they are especially used as substitute materials for metals in industrial parts, electrical parts, office machine housings, automobile parts, precision parts, etc. Widely used for parts, etc. In recent years, home appliances such as radios and televisions, wireless devices such as transceivers, various electronic measuring instruments,
In the field of office equipment housings and the like, there is an increasing demand for thermoplastic resins to be made electrically conductive, as exemplified by electromagnetic shielding regulations (EMI regulations). Various technical studies have been conducted regarding methods of imparting conductivity to thermoplastic resins. for example,
Attempts have been made to apply conductive paint to molded products, to form a thin metal film on the surface of molded products using an electroless plating process, and to mix and disperse conductive fibers in thermoplastic resin. However, with the method of applying conductive paint, it is difficult to maintain the uniformity of the paint film on complex molded products, and it is difficult to maintain the adhesion between the base thermoplastic resin and the paint. There is a need to select the most suitable paint, and there are problems with environmental pollution during the painting process. The electroless plating method requires plating tank equipment and has the disadvantage that the molded product itself becomes entirely metallic. From the above, currently, the method of imparting conductivity by mixing and dispersing conductive fibers into a thermoplastic resin is currently attracting the most attention. Specifically, Japanese Patent Publication No. 59-19480 discloses a material for shielding electromagnetic waves in which conductive fibers and conductive fine powder are dispersed in a resin, and Japanese Patent Publication No. 58-79050 discloses a material for shielding electromagnetic waves in which conductive fibers and conductive fine powder are dispersed in a resin. A polyphenylene ether resin composition for electromagnetic interference shielding mixed with aluminum flakes, carbon fibers, etc. is shown. However, since the base thermoplastic resin is originally an electrical insulator, in order to impart the desired electrical conductivity, it has been necessary to use relatively large amounts of expensive conductive fiber filaments or chopped fibers. It becomes necessary to add and mix strands or conductive powder, which not only deteriorates the original physical properties of the matrix, but also causes a significant decrease in manufacturing yield due to fibrillation of the conductive fibers, resulting in high prices and products. In terms of value, it tends to be insufficient, and improvements have been requested. Several improved techniques have been studied in the past regarding methods for producing conductive thermoplastic resins containing these conductive fibers. For example, in JP-A No. 59-22710, ABS resin is used as the thermoplastic resin, an extruder is used, a carbon fiber filament bundle coated with metal plating etc. is uniformly coated with synthetic resin at the center, and then cut. A method for obtaining an excellent conductive molding material for shielding electromagnetic waves in electronic devices, in which carbon fiber filler is uniformly dispersed and has good plasticization, has been disclosed, and Japanese Patent Application Laid-Open No. 1986-
21734, as shown in Figure 4, thermoplastic synthetic resins (e.g. polyethylene, polypropylene,
ABS resin, etc.) is plasticized using, for example, a screw extruder a, and then extruded into a thin sheet from a T-die b. At a position where this sheet c is at a temperature higher than its softening point, or while being kept at a temperature higher than its softening point using an infrared lamp or the like, conductive foil pieces or conductive fibers d ( (e.g. metal foil pieces, metallized glass short fibers, carbon short fibers, etc.) are dropped and deposited in layers, and then the whole is passed between a pair of pressure rolls or belts e to separate sheet c and layer f. A method for obtaining a synthetic resin molding material by pressure-integration is shown. In JP-A No. 59-49913, strand-like or roving-like metal thread fibers are unraveled in a die of an extruder and coated with a thermoplastic synthetic resin to disperse conductor fibers well in the resin. Regarding a manufacturing method that also increases the aspect ratio of the molten resin, conductor fibers such as metal fibers or carbon fibers are introduced from the fiber inlet i of the mandrel h provided in the direction perpendicular to the molten resin inlet g, as shown in Fig. 5B. , pulled out from the fiber outlet j. Next, the fibers are passed through the outer periphery of a conical or polygonal pyramid-shaped fiber guide k to spread the fibers radially, and the resin and fibers that have reached the nozzle introduction part r are entangled with each other and guided to the nozzle land part m. A method is shown in which the resin o covering the conductive fibers n, taken off by a take-off machine after cooling and solidifying, is cut with a pelletizer to obtain pellets p as shown in FIG. 5A. However, in JP-A No. 59-22710, a special carbon fiber filament coated with metal plating is used to impart conductivity, and in JP-A No. 58-21734, a thermoplastic resin matrix is formed into a sheet. In fact, in JP-A No. 59-49913, there is a restriction on making special improvements to the die part of the extruder, which is not practical. [Problems to be Solved by the Invention] The present inventors used an ordinary extruder and a conductive fiber chop strand, and achieved a method with little deterioration in physical properties.
The present invention was arrived at after extensive research into a simple method for producing a thermoplastic resin with good conductivity. [Means and effects for solving the problem] The present inventors have proposed a conventionally used method for adding conductive fiber chopped strands to a thermoplastic resin, for example, a method for adding conductive fiber chopped strands to a thermoplastic resin. In the method of uniformly mixing conductive fiber chopped strands in advance and feeding them through the extruder hopper port for extrusion mixing, the manufacturing yield due to defibration, classification, etc. by the conductive fiber chopped strands is significantly reduced. Not only that, when the thermoplastic resin is melted, the chopped strands of conductive fibers are significantly damaged due to the shear stress they receive, and the fiber length becomes extremely short, resulting in decreased conductivity and physical properties. I found something to do. Based on these analysis results, the conductive fiber chopped strands can be defibrated,
As a result of various studies on a method that does not require classification and maintains the fiber length as long as possible, we have found that chopped strands of conductive fibers are precisely added to pre-molten thermoplastic resin and mixed with high precision to achieve conductivity. The present invention was accomplished by discovering that this is essential in order to obtain a conductive thermoplastic resin composition with good physical properties. By using the method of the present invention, a thermoplastic resin with excellent conductivity can be provided to the market at a low cost, with a high production yield and little deterioration of physical properties using a small amount of chopped conductive fiber strands. It is thought that it will be possible to do so. The present invention provides two or more supply ports 1a as shown in FIG.
Using an extruder A having an extruder 1b, a thermoplastic resin as a base material is supplied from the first and supply port 1a (hopper port),
A quantitative feeder is used to supply a constant supply amount, and the melted and kneaded state is supplied to the second and subsequent supply ports 1b.
Using a vibrating electric feeder, the conductive fiber chopped strands are fed in a fixed quantity from the (vent port) with extremely high accuracy, and the conductive fiber chopped strands are added and kneaded so that the content of the conductive fiber chopped strands is 0.5 to 50% by weight. The present invention relates to a method for producing a conductive iron-plastic resin, which is characterized by the following. When used in the production method of the present invention, it is possible to maintain the number average fiber length of the chopped strands of conductive fibers at 0.2 mm or more, with little deterioration of physical properties and extremely good conductivity. A low-cost conductive thermoplastic resin can be obtained. In the present invention, it is essential to be able to quantitatively supply the chopped strands of conductive fiber to the extruder supply port with extremely high accuracy, and a vibrating electric feeder is most suitable as a quantitative feeder for this purpose. There are many types of quantitative feeders, such as screw feeder type, table feeder type, pressure feeder type, etc., but chopped strands of conductive fiber are usually very easy to defibrate by vibration, movement, stirring, etc. For example, the quantitative accuracy is extremely poor with rotary volumetric methods such as screw feeders.
This not only causes a decrease in production yield, but also
Quality cannot be stabilized either. The vibrating electric feeder according to the present invention is a gravimetric quantitative feeder consisting of a trough that transports materials by vibrating with an electromagnet, and a conveyor that is driven at a constant speed and has a weight detection device. One example is the format shown in Figure 2. Its components include a hopper section 2 for storing chopped conductive fiber strands, a trough 3 for transporting materials, an electromagnet 4 attached to the center of the trough as a vibration source, a movable frame 5 and a vibration source attached to both ends of the hopper section 2. It consists of a leaf spring 6 whose angle can be freely varied and its control equipment. The principle of operation is that when the electromagnet 4 is excited, the trough supported by the leaf spring 6 is suddenly drawn diagonally downward. Since the excitation current is a pulsating current, the magnetic force disappears at the point where the current is zero, and the trough 3 is pushed back forward by the repulsive force of the leaf spring 6. At this time, the material on the trough 3 is moved forward and at a constant speed. It is fed onto a driving conveyor 7. The weight of the material on the conveyor 7 is detected by a load cell 8, the output voltage of which is compared with a set voltage corresponding to a preset transport vehicle set value.
The error resulting from the comparison, that is, the difference voltage between the output voltage of the load cell 8 and the set voltage, is transferred to the PID operational amplifier 9.
and the amplified voltage causes thyristor 1 to be amplified.
The feeder cutting amount is adjusted by controlling the zero firing angle and changing the voltage to the electromagnet. The vibration angle of this trough 3 can be flexibly adjusted by adjusting the mounting angles (β ₁ , β ₂ ) of the leaf springs 6, so that optimum vibration characteristics suitable for the material to be transported can be obtained.
For example, if the bulk density is relatively low, such as a chopped conductive fiber strand, and the fibers are likely to unravel due to jumps during transportation or deviations in width at the trough outlet, the installation angle of the leaf spring 6 may be By increasing the angle of vibration and reducing the angle of vibration, the accuracy of quantitative feeding is significantly improved. On the other hand, in the case of heavy items, it is possible to secure the necessary angle by changing the mounting angle.
Preferred conditions in the present invention are a trough vibration angle of 90 to 60 degrees and a vibration frequency of 2000 to 3000 times/min. An example of such a machine is the linear syntron gravimetric feeder manufactured by Kamami Electric Co., Ltd.
It is commercially available as the LF type. In Figure 2, 11 is a synchro motor, 12 is a fulcrum, 13 is an instantaneous transport amount indicator, and 14 is a synchronized motor.
is an instantaneous transport amount setting device, 15 is a manual/automatic switching device,
16 is a voltmeter, and 17 is a fixed frame. Furthermore, the extruder used in the present invention is not particularly limited as long as it is equipped with two or more supply ports, and it is sufficient as long as the barrel temperature can be controlled between 100°C and 350°C. It is possible to use an extruder such as a machine or a twin-screw extruder (same-direction rotation type, opposite-direction rotation type), but in cases where a relatively large amount of chopped strands of conductive fiber is added. A twin-screw extruder is preferred. Further, there is no particular restriction on the screw dimension, and various types of screw dimensions can be constructed if necessary, depending on the thermoplastic resin used as the base material. The chopped strand of conductive fiber used in the present invention is not particularly limited as long as it is conductive itself, and metal fibers such as gold, silver, copper, nickel, aluminum, and iron, glass fiber, and silicone can be used. The above metals are plated, vapor-deposited, etc. on fibers that themselves have no or almost no conductivity, such as carbide fibers, boron fibers, organic high-elastic fibers, polyester fibers, and polyamide fibers.
Materials that have been thermally sprayed to provide conductivity or chopped strands such as carbon fiber are used, but carbon fiber has high strength and high elasticity, so it has a large reinforcing effect on resin, and carbon fiber has a low specific gravity. Chopped strands are preferred, more preferably,
Carbon fiber chopped strands having an angle of repose of 35 to 45 degrees and a bulk density of 0.15 to 0.45 g/cm ³ are preferred. Furthermore, there are no particular restrictions on the thermoplastic resin used as the base material in the present invention, and polyolefin resins, polyvinyl chloride resins, styrene resins,
Any one type or a combination of two or more of thermoplastic resins such as polycarbonate resin, polyphenylene ether resin, acrylic resin, polyamide resin, polyester resin, and polyphenylene sulfide resin can be used. If desired, reinforcing agents such as stabilizers, anti-aging agents, colorants, flame retardants, reinforcing elastomers, inorganic fillers, and glass fibers can also be added. [Example] The method of the present invention will be described in detail in the following Examples. The characteristics of various raw materials and the physical properties of the conductive thermoplastic resin shown in the Examples were determined by the following methods. Bulk density of carbon fiber chopped strand (g/
cm ³ ) In a glass cylindrical bottle with a diameter of 3 cm and a height of 8 cm,
Precisely weigh 2 g of chopped carbon fiber strands and seal with a cork stopper. This sample was manufactured by Irie Shokai Co., Ltd.
After shaking for 1 hour at 23° C. using a Type-3 shaker, the carbon fiber chopped strands are measured for height, volume, and bulk density.
The carbon fiber chopped strand with a higher bulk density value is less defibrated by vibration and has better quantitative accuracy. Angle of repose (degrees) of carbon fiber chopped strand The angle of repose of the carbon fiber chopped strand was measured at 23℃ using an angle of repose measuring device KRS model manufactured by Kuramochi Kagaku Kikai Seisakusho. The fluidity is better, less fibrillation occurs, and the quantitative accuracy is better. Content of chopped carbon fiber strands in conductive thermoplastic resin (wt%) 2 g of conductive thermoplastic resin was accurately weighed, and heated in air at 450 °C using a Tanaka Kagaku Kikai heating furnace, SOFTEMP-F type. After baking at a temperature of 2 hours at a temperature of 0.degree. C., the thermoplastic resin is burned out, the weight of the remaining carbon fibers is measured, and the carbon fiber content is expressed in weight %. Measurement of fiber length of chopped carbon fiber strands in conductive thermoplastic resin (mm) Using approximately 0.1 g of residual carbon fiber fired in a heating furnace at 450°C, using a CARLZEISS binocular stereoscopic microscope. Observe the distribution morphology of carbon fiber chopped strand fiber length using
The carbon fiber chopped strand was cut out, the fiber length was measured, and the number average length (mm) of the chopped carbon fiber strand was determined by the following method. Number average length Σn・d/Σn n: Number of carbon fiber chopped strands d: Diameter of carbon fiber chopped strands (mm) Measurement of conductivity (surface resistivity) (Ω) Width 5 cm, length Conductive thermoplastic resin was molded using an 8.9 cm, 2 mm thick direct gate flat plate mold using an IS-80A injection molding machine manufactured by Toshiba Machinery Co., Ltd.
℃, 50% humidity for 24 hours, conductive paste (Tokuriki Chemical Research Institute Silvest P-
255) to a width of 2 mm, and Sanwa Denki Co., Ltd.
The resistance value Ω between the conductive pastes was measured using a manufactured tester SH-63TR-D type tester, and the distance between the electrodes (distance between conductive pastes 5 cm) was removed by the effective length of the electrodes (conductive paste application length 5 cm). , multiplied by the resistance value to measure the surface resistivity. In FIG. 3, l ₁ =5 cm, l ₂ =8.9 cm, l ₃ =5 cm, and l ₄ =2 mm. The thickness of the sample in Figure 3 is 2 mm. Surface resistivity (Ω) = distance between electrodes/effective length of electrode x resistance value Flexural modulus Conductive thermoplastic resin is made of IS-80A manufactured by Toshiba Machine Co., Ltd.
Using an injection molding machine, create a test piece and pass ASTM D
-790 is used to measure the flexural modulus. Heat deformation temperature Conductive thermoplastic resin is manufactured by Toshiba Machine Co., Ltd. IS-80A
Using an injection molding machine, create a test piece and pass ASTM D
-648, fiber burst stress 18.6Kg/cm ²
Measure the heat distortion temperature. Izotsu impact strength Test specimens are prepared from conductive thermoplastic resin using an IS-80A injection molding machine manufactured by Toshiba Machine Co., Ltd., and ASTM D
−256, with a notched specimen of 1/4″ thickness,
Measure the Izot impact strength at 23℃. Example 1 A PCM-87 twin-screw extruder (manufactured by Ikegai Tekko Co., Ltd.) was used as an extruder equipped with two _or more supply ports. Shinko Electric as a vibrating electric feeder
Install Linear Cintron LF-40 model manufactured by Co., Ltd., _and
C The temperature of the barrel, which can be adjusted in ₇ parts and 7 steps, is set to 250°C for the die part and 250°C for the head part.
250℃, ₇ parts of C 240℃, ₆ parts of C at 240℃, ₅ parts of C at 240℃,
₄ parts of C were set at 260°C, ₃ parts of C at 270°C, ₂ parts of C at 270°C, and ₁ part of C at 260°C, and the screw rotation speed was set at 50 rpm. Next, from the first supply port of the extruder feed section, the polymerization degree is
20 parts by weight of 2,6-dimethyl 1,4-phenylene ether resin of 150, 45 parts by weight of Amilan 1017 (manufactured by Toray Industries, Inc.) as a polyamide resin, and Dilarc 232 as a styrene-maleic anhydride copolymer resin.
(manufactured by ARCO) and 0.5 parts by weight of Irganox 1076 (manufactured by Ciba-Geigi) as a stabilizer were uniformly mixed in a blender and adjusted to 80 kg/hr using a screw type quantitative feeder. , to quantitatively feed the twin-screw extruder. Next, Torayca T-006 manufactured by Toray Industries, Ltd. (6 cm length, high bulk) was used as the carbon fiber chopped strand to impart conductivity.
0.25g/cm ³ , angle of repose 44 degrees) as a linear synthron
Pour into the hopper for the LF-40 type vibrating electric feeder, adjust the feed rate to 20Kg/Hr,
The melted thermoplastic resin is quantitatively supplied from the barrel block section of the twin-screw extruder C, which is the _second supply port, to produce conductive thermoplastic resin containing chopped carbon fiber strands. Ivy. Regarding manufacturing stability, there was no surging (pulsation) or strand breakage due to the precision of quantitative feeding of carbon fiber chopped strands, and the manufacturing yield was 98.
It was %. The physical properties and analysis results of the obtained resin properties are shown in Table 1. Example 2 Using the same equipment as in Example 1, the die part was heated to 260°C, the head part to 260°C, and the head part to 260°C.
₇ parts of C at 250°C, ₆ parts of C at 250°C, ₅ parts of C at 250°C, ₄ parts of C at 270°C, ₃ parts of C at 280°C, ₂ parts of C at 280°C, ₁ part of C
The temperature was set at 270°C and the screw rotation speed was set at 50 rpm. 5 parts by weight of 2,6-dimethyl 1,4-phenylene ether resin with a degree of polymerization of 150 as the base thermoplastic resin component, 70 parts by weight of Amilan 1017 (manufactured by Toray Industries, Inc.) as the polyamide resin, and 5 parts by weight of Dilarc 232. Conductivity was maintained under the same conditions except that a modified lot of Toray T-006 (bulk density 0.28 g/cm ³ , angle of repose 38 degrees) was used as the carbon fiber chopped strand. Compared to Example 1, in which a thermoplastic resin was manufactured, the chopped strands have a higher bulk density and a lower angle of repose, so the flowability of the chopped strands is better. The quantitative supply accuracy of the chopped fiber strands was also better, the production yield was as high as 97%, and the production stability was also extremely good. Table 1 shows the physical properties and analysis results of the obtained resin. Example 3 Compared to Example 1, Hercules Magnamite 1800AS (6 mm length, bulk density
Conductive thermoplastic resin was produced using the same method and conditions as Matsutaku, except that the carbon fiber was changed to 0.20 g/cm ³ and angle of repose of 39 degrees).The precision in quantitative feeding of chopped carbon fiber strands was also good. The manufacturing yield was 99%, and the manufacturing stability was also good. The physical properties and analysis results of the resin properties obtained are shown in Table 1. Example 4 In Example 1, instead of using the carbon fiber chopped strand alone, Torayka T-006 manufactured by Toray Industries, Inc. (bulk density 0.25 g/
cm ³ , angle of repose 44 degrees) 50% by weight, and Asahi Fiberglass Co., Ltd. MA as chopped glass fiber strands.
−419 (6 mm length, bulk density 0.38 g/cm ³ , angle of repose 30
A conductive thermoplastic resin was produced using the same method and conditions as in Example 1, except that the mixed chopped strands were changed to 50% by weight. Compared to the carbon fiber chopped strand alone, the bulk density was higher and the angle of repose was lower, so the quantitative supply accuracy was extremely high and the manufacturing stability was also good. Table 1 shows the physical properties of the obtained resin and the analysis results. Regarding the conductivity, since the carbon fiber content was 1/2 that of Example 1, the conductivity decreased by the amount of the content. Example 5 Using exactly the same equipment as in Example 1, the barrel temperature was set from the die side to 320°C for the die part, 320°C for the head part, 310°C for _{the C7} part, 310°C for the _C6 part, and 310°C for the _{C5 part.} Department
310℃, ₄ parts of C at 330℃, ₃ parts of C at 330℃, ₂ parts of C at 330℃
℃、C ₁ part is set to 320℃ and the screw rotation speed is
I set it to 50rpm. Next, from the first supply port of the extruder feed section, 30 parts by weight of 2,6-dimethyl-1,4-phenylene ether resin with a degree of polymerization of 120 and a rubber-modified impact-resistant polystyrene resin were added as the base thermoplastic resin component. , 43 parts by weight of Styron 492 (manufactured by Asahi Kasei Corporation), 7 parts by weight of triphenyl phosphate as a flame retardant, and 0.5 parts by weight of Irganox 1076 (manufactured by Cibagai Gi) as a stabilizer were uniformly mixed in a blender using a screwdriver. Adjust the amount to 80Kg/Hr using a feeder-type quantitative feeder and quantitatively feed it to the twin-screw extruder.
Next, Torayca T-006 manufactured by Toray Industries, Inc. (6 mm length, bulk density 0.25 g/cm ³ , angle of repose 44 degrees) was used as a chopped carbon fiber strand to impart conductivity to a Linear Syntron LF-40 type vibrator. The carbon fibers were poured into a popper for an electric feeder, adjusted so that the feed rate was 20 kg/hr, and quantitatively fed into the molten thermoplastic resin from the barrel block of _{the 4th} section of the twin-screw extruder C. A conductive thermoplastic resin containing rolled strands was manufactured. The manufacturing stability was good, with no surging (pulsation) or strand breakage caused by the precision of quantitative feeding. The physical properties and analysis results of the obtained resin properties are shown in Table 1. Example 6 Using the same conditions and equipment as in Example 2, Amiran 1017 (manufactured by Toray Industries, Inc.) was used as the polyamide resin as the thermoplastic resin component, and the amount was adjusted to 85 Kg/Hr using a screw type quantitative feeder. Adjust and quantitatively feed to the twin-screw extruder. Next, as a chopped carbon fiber strand, Torayka T-006 (6 mm length, bulk density 0.25 g/cm ³ , angle of repose)
A conductive thermoplastic resin was produced under the same conditions as in Example 2, except that the feed rate was adjusted to 15 Kg/Hr. The manufacturing stability was also very good. Table 1 shows the physical properties and analytical values of the resin obtained. Example 7 A conductive thermoplastic resin was produced in the same manner and under the same conditions as in Example 5, except that the thermoplastic resin component was changed to 80 parts by weight of polycarbonate resin Teijin Panlite L-1225. . The production yield was 95%, and the production stability was also good. Table 1 shows the physical properties and analytical values of the resin obtained. Comparative Example 1 In contrast to Example 1, Besphite HTA- manufactured by Toho Rayon Co., Ltd. was used as the chopped carbon fiber strand.
6-S (6mm length, bulk density 0.13g/cm ³ , angle of repose 49
Example except that Acrison's 105Z positive displacement quantitative feeder was used as the screw feeder type quantitative feeder instead of a vibrating electric feeder as the carbon fiber chopped strand quantitative feeding device. A conductive thermoplastic resin was produced using the same method and conditions as in Example 1. Compared to Example 1, the bulk density of the chopped carbon fiber strands was significantly lower and the angle of repose was also larger, resulting in very poor flowability and a commercially available screw feeder type quantitative feeder was used. In addition, due to the rotation of the screw during metering in the metering feeder, the chopped carbon fiber strands significantly defibrate each other, causing intermittent unevenness in metering, which significantly deteriorates the precision of metering, and as a result, production stability deteriorates. , surging caused by pulsation occurred frequently, strand breakage occurred, the production yield decreased to 55%, the production stability was extremely insufficient, and samples for evaluation of physical properties could not be prepared. Table 1 shows the analysis results of the obtained resin composition. Comparative Example 2 Using the same method and conditions as in Comparative Example 1, Toray Industries, Inc.'s Trading Card T-006 (6 mm length, bulk density) used in Example 1 as a chopped carbon fiber strand was used. 0.25g/cm ³ , angle of repose 44 degrees),
Manufactured conductive thermoplastic resin. Compared to Comparative Example 1, even if carbon fiber chopped strands with high bulk density, low angle of repose, and good fluidity were used, a vibrating electric feeder was not used as shown in Example 1, Since a commercially available screw feeder was used as a quantitative feeding device for carbon fiber chopped strands, the carbon fiber chopped strands were significantly defibrated due to the screw rotation of the quantitative feeder, resulting in intermittent unevenness in quantitative measurement. As a result, the accuracy of fixed quantity supply deteriorated significantly, and as a result, production stability was affected by frequent surging due to pulsation, frequent occurrence of strand breakage, and low production yield of 75%.
The manufacturing stability was insufficient. Table 1 shows the analysis results of the obtained resin composition. Comparative Example 3 As an extruder equipped with two or more supply ports,
A PCM-87 twin-screw extruder (manufactured by Ikegai Tekko Co., Ltd.) was used, and one supply port on the die side was left open to the atmosphere without a vibrating electric feeder installed. Next, the barrel temperature was set to 250℃ from the die side to each die part.
Head part 250℃, _C7 part 240℃, _C6 part 240℃, _C5
240°C for ₄ parts, 260°C for 3 parts, 270°C for ₃ parts, and ₂ parts for C.
The temperature was set at 270°C, the C ₁ part was set at 260°C, and the screw rotation speed was set at 50 rpm. Next, from the first supply port of the extruder feed section, 20 parts by weight of 2,6-dimethyl 1,4-phenylene ether resin with a degree of polymerization of 150 was added as a conductive thermoplastic resin component, and Amilan 1017 (Toray Industries, Inc.) was added as a polyamide resin. 45 parts by weight of Dilarc 232 (manufactured by ARCO) as a styrene-maleic anhydride copolymer resin, 0.5 parts by weight of Irganox 1076 (manufactured by Cibagai Gi) as a stabilizer and Toray as a chopped strand of carbon fiber. A resin made by uniformly mixing 20 parts by weight of Torayca T-006 (6 mm length, bulk density 0.25 g/cm ³ , angle of repose 44 degrees) manufactured by Co., Ltd. in a blender was added to the screw-type quantitative feeder.
The conductive thermoplastic resin was adjusted to 100 Kg/Hr and quantitatively fed to a twin-screw extruder to produce a conductive thermoplastic resin. Regarding production stability, although there was a slight occurrence of surging and some occurrence of strand breakage, the production yield was 80%. Table 1 shows the physical properties and analysis results of the resin properties obtained. Example 1
On the other hand, since the carbon fiber length in the composition was short, the conductivity decreased, and the impact strength, flexural modulus, and heat denaturation temperature decreased. Comparative Example 4 As an extruder equipped with two or more supply ports,
A PCM-87 twin-screw extruder (manufactured by Ikegai Tekko Co., Ltd.) was used, and one supply port on the die side was left open to the atmosphere without a vibrating electric feeder installed. Next, the barrel temperature was set to 320℃ from the die side to each die part.
Head part 320℃, _C7 part 310℃, _C6 part 310℃, _C5
310℃ for ₄ parts of C, 330℃ for ₃ parts of C, ₂ parts of C
The temperature was set at 330°C, the _C1 part was set at 320°C, and the screw rotation speed was set at 50 rpm. Next, from the first supply port of the extruder feed section, 30 parts by weight of 2,6-dimethyl-1,4-phenylene ether resin with a degree of polymerization of 120 and a rubber-modified impact-resistant polystyrene resin were added as a conductive thermoplastic resin component. 43 parts by weight of Styron 492 (manufactured by Asahi Kasei Corporation), 7 parts by weight of triphenyl phosphate as a flame retardant, 0.5 parts by weight of Irganox 1076 (manufactured by Cibagai Gi) as a stabilizer, manufactured by Toray Industries, Inc. as a chopped carbon fiber strand. Trading card T
-006 (6mm length, bulk density 0.25g/ ^cm3 , angle of repose 44
The resin was uniformly mixed with 20 parts by weight) in a blender, adjusted to 100Kg/Hr using a screw feeder-type quantitative feeder, and quantitatively fed to a twin-screw extruder. Manufactured resin. Regarding production stability, there was a slight occurrence of surging and occasional strand breakage, but the production yield was 82%. Table 1 shows the physical properties and analysis results of the obtained resin.
Shown below. Compared to Example 5, since the carbon fiber length in the composition was short, the conductivity decreased, and the impact strength, flexural modulus, and heat distortion temperature decreased. Comparative Example 5 Compared to Comparative Example 4, 27 parts by weight of 2,6-dimethyl-1,4-phenylene ether resin with a degree of polymerization of 120 was used as the conductive thermoplastic resin component, and 40 parts by weight of Stylon 492 was used as the rubber-modified impact-resistant polystyrene resin. Part by weight, triphenyl phosphate 3 as flame retardant
Part by weight, 0.5 part by weight of Irganox 1076, Toray Industries, Inc. T-006 (6 parts by weight) as chopped carbon fiber strand.
A conductive thermoplastic resin was produced in the same manner and under the same conditions as in Comparative Example 4, except that the amount was changed to 30 parts by weight (mm length, bulk density 0.25 g/cm ³ , angle of repose 44 degrees). Due to the large amount of carbon fiber chopped strands,
Fibrillation was severe, surging occurred frequently, strand breakage was severe, and the production yield decreased to 40%, making production difficult. Table 1 shows the physical properties and analytical values of the resin obtained. Compared to Example 5, although the carbon fiber chopped strand content was high, the fiber length was short, the conductivity was low, and the impact strength and heat distortion temperature were also low.

【table】

【table】

【table】

[Table] * indicates a mixed product of carbon fiber chopped strands and glass fiber chopped strands [Effects of the invention] As described above, in the present invention, conductive fiber chopped strands are produced using a vibrating electric feeder. Since the chopped strands are added from the extruder vent, it is possible to precisely add and mix the chopped conductive fiber strands to the pre-molten thermoplastic resin, and the shear stress received during the manufacturing stage is reduced. Since fiber breakage can be reduced and fiber length can be prevented from shortening, a conductive thermoplastic resin composition with good conductivity and physical properties can be obtained at a high production yield, and its industrial significance is great.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an extruder as part of the apparatus used in carrying out the method of the present invention;
Fig. 2 is a schematic explanatory diagram showing a vibrating electric feeder, Fig. 3 is a plan view showing a sample for conductivity measurement, and Figs. 4 and 5 A and B are schematic explanatory diagrams showing conventional technology. . A... Extruder, 1a, 1b... Supply port, 2...
Hopper, 3...Trough, 4...Electromagnet, 5...
Movable frame, 6... leaf spring, 7... constant speed belt conveyor, 8... load cell, 9... PID operational amplifier, 10... thyristor, 11... synchronized motor, 12... fulcrum, 13... instantaneous transport Quantity display meter, 14... Instantaneous transport amount setting device, 15... Manual/automatic switching device, 16... Voltmeter, 17... Fixed frame, 18... Conductive paste.

Claims (1)

[Claims] 1. A method for producing a conductive thermoplastic resin, characterized in that chopped strands of conductive fiber are added from a vent section of an extruder using a vibrating electric feeder. 2. The method for producing a conductive thermoplastic resin according to claim 1, wherein the conductive fiber chopped strand is a carbon fiber chopped strand. 3 The angle of repose of the chopped carbon fiber strand is 35
3. The method for producing a conductive thermoplastic resin according to claim 2, wherein the temperature is 45 degrees. 4 The bulk density of the chopped carbon fiber strand is
4. The method for producing a conductive thermoplastic resin according to claim 3, wherein the conductive thermoplastic resin is 0.15 to 0.45 g/cm ³ .