JPS627509A - Manufacture of resin composite material mixed with carbon fiber - Google Patents

Abstract

PURPOSE:To enable to uniformly disperse carbon fibers without using binder by a method wherein fibrous carbon fibers are supplied in such a manner as to be nipped by the screw in the barrel of an extruder together with thermoplastic resin in order to cut the carbon fibers into chips and at the same time to mix with the resin and finally to extrude the fibers and the resin in composite form. CONSTITUTION:Thermoplastic resin 5 is supplied to the hopper port 2 of a screw type extrusion machine, the temperature at the extruding outlet of which is kept at a temperature higher than the melting temperature of the thermoplastic resin. At the same time, tow-like or filament yarn-like carbon fibers 3 are supplied through the hopper port 2 or the second hopper port 2', which is provided in the downstream of the hopper port 2, into the barrel 4 of the extrusion machine is such a manner as for the fibers to be nipped by the screw of the extrusion machine. The carbon fibers are cut through the rotation of the screw 6 in the barrel 4 into chips and mixed with the resin so as to be extruded in composite form. Resin composite material mixed with carbon fibers, which are in chopped form and dispersed in the resin, is obtained during a single process and without using binder by supplying the carbon fibers in two-like or filament yarn-like form as they are in the screw type extruding machine together with the thermoplastic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a carbon ##ll fiber-containing resin composite material in which chopped carbon fibers are uniformly dispersed in a resin.

[Prior art] Carbon mla has high tensile strength and elastic modulus as well as electrical conductivity, so it can be used as a composite material (CF
RP) is used as a so-called reinforced plastic for the purpose of preventing static electricity and preventing electromagnetic interference. Among these, composite materials with thermoplastic resins (CFR-TP) are expected to be used more widely in the future because they can be injection molded or blow molded and are easy to handle.

In the case of the above-mentioned CFR-TP, chopped fibers with a length of about 3 to 10 mts are conventionally used as the carbon fibers, and this is done by first cutting long m fibers into a chopped shape. The two-step process involved mixing the chopped material with molten polymer to obtain a carbon fiber-containing resin composite. When cutting these long fibers, the long fibers are often bundled in advance using a sizing agent in order to facilitate cutting and improve dispersibility during mixing.

[Problems to be solved by the invention] However, this sizing agent has a different affinity depending on the resin used, so it must be carefully selected.On the other hand, when no sizing agent is used, carbon There was a problem in that only the fibers clumped together to form so-called fiber poles, making uniform mixing difficult. Furthermore, since the manufacturing process involves two steps as described above, it is not economical.

Therefore, an object of the present invention is to supply carbon fiber in the form of tow or filament thread together with a thermoplastic resin so as to be bitten into a screw in an extruder barrel, cut the carbon fiber into chops, and mix it with the resin to form a composite. An object of the present invention is to provide a method for manufacturing a carbon fiber-containing resin composite material, which can obtain a composite material in which chopped carbon fibers are uniformly dispersed in a very cylindrical manner without using a sizing agent by extruding the carbon fibers.

[Means for Solving the Problems] In order to solve the above problems, the present invention supplies a thermoplastic resin to the hopper mouth of a screw type extruder in which the extrusion exit temperature is maintained above the melting temperature of the thermoplastic resin. At the same time, tow-like or filament-like carbon t is released from the hopper mouth or a second popper mouth provided further downstream.
A configuration in which a#I is fed into the extruder barrel so as to be bitten by the screw, and the carbon fibers are cut into chop shapes by the rotation of the screw in the extruder barrel, mixed with the resin, compounded, and extruded. are taken.

[Function] The present inventors investigated a simple method for mixing and dispersing chopped carbon fibers in a polymer. or filamentous l
It was discovered that a carbon fiber-containing resin composite material in which thick-shaped carbon fibers are uniformly dispersed in the resin can be obtained extremely easily by supplying the a-male together with the thermoplastic resin so as to fit into the screw, leading to the present invention. .

According to the present invention, carbon fibers in the form of tows or filaments are cut into chops by the shearing force applied to the fibers or the mixture of resin and fibers in the barrel by the rotation of the screw, and mixed with the resin at the same time. and compounded. Therefore, there is no need to take the two-step process of cutting the length m#I into chops and then melt-mixing it with the polymer as in the conventional method. There is no need to use a sizing agent to improve dispersibility.

Further, since the tow-like or filament-like carbon fiber is automatically and continuously drawn into the barrel when it is bitten by the screw, it is easy to supply am.

In addition, carbon fibers are added to the manufactured tow (typically about 3
0c ■, approximately 400 discontinuous rams with a diameter of approximately 2oIL
00 fibers bundled into an apparently infinite length fiber bundle) can be directly composited without being cut into chops in advance. The effectiveness of the present invention is clear when compared to the fact that it is difficult to bundle short #I fibers for tow. One-strand firing can also be applied to pre-bound long fibers or surface-treated m#I.

[Specific Examples of the Invention] Further, the present invention will be explained in detail with reference to FIGS. 1(A) and 1(B).

In the present invention, a tow-shaped fiber (for example, about 40,000 discontinuous fibers with a length of about 30 cm + * and a diameter of about 20 = is bundled into a seemingly infinite fiber bundle from the popper port 2 of the screw extruder 1). ) or filamentary carbon m'la3 is fed into the barrel 4 together with the thermoplastic resin 5. Carbon edge! After being supplied, the i13 is eventually bitten by the screw 6, so that the thermoplastic resin 5 is automatically and continuously drawn into the barrel 4 from the hopper 2, and the carbon fiber 3 from the hopper 2 or 2'. Inside barrel 6,
The tow-like or filament-like carbon HHa is cut into chops by the shearing force generated by the rotation of the screw 6. Inside the barrel 4, a heater 7 keeps the extrusion exit temperature above the melting temperature of the thermoplastic resin, and the rotation of the screw 6 cuts the carbon fiber 3 and separates the carbon tam and thermoplastic resin. Mixing or compounding is performed. The composite resin is extruded through a die 8 which is maintained at a temperature higher than the melting temperature of the resin, and is cooled through a water tank lO as shown in the figure to form a strand 9.

It can be cut into pellets or hot-cut without passing through a water bath to produce carbon fiber-containing resin berets. By performing strand cutting or hot cutting in this manner, the carbon fibers can be cut more reliably. Thereafter, this pellet can be molded to obtain a desired molded product.

Furthermore, the resin composited within the extruder barrel 4 can be processed into films, sheets, and other molded products directly from the extruder without being pelletized.

As the carbon fiber used in the present invention, any type of carbon fiber currently produced, regardless of whether it is a PAN type or a pitch type, can be used. In addition, the thermoplastic resins used include polyethylene, polypropylene, polystyrene,
Polyvinyl chloride G') J: Una general purpose resin, EVA, EE
A, AS resin, copolymer resin such as ABS, polyamide resin, polyacetal, polycarbonate, modified PPO,
General-purpose engineering plastics such as PBT and PET and all other thermoplastic resins are used.

The amount of carbon fiber mixed into the resin is preferably 5 to 50 wt%; if it is less than 5 wt%, there is no effect of adding carbon fiber;
If it exceeds 50 wt%, the cost will increase and at the same time the properties as a resin will be lost during kneading.

Note that the screw of the screw type extruder may be either single or multi-screw, and the die at the exit of the extruder may be single-hole or multi-hole, and if the die is multi-hole, it is possible to extrude a plurality of strands at the same time.

r Example] Next, the effects of the present invention will be clarified in Examples.

(Example 1) (See Figure 1 (A)) Kinoshita Manufacturing Department equipped with a full-flight single screw,
The wire mesh (screen) at the exit of the extruder was removed from the electrically heated 45-layer extruder, and a breaker plate and a gouie with a cylindrical nozzle were attached. The die temperature was set at 220° C., and operation was started at a screw rotation speed of 72 rpm.

Next, pellets of polypropylene resin rAZ-564J manufactured by Sumitomo Chemical Co., Ltd. were supplied from the hopper of the extruder. The polymer is extruded from a die with a diameter of 4 m attached to the die, cooled in a water tank, and cut into a length of 4 m with a cutter.
Cut into layers cylindrical pellets. In this state, from the hopper mouth, carbon @jirT101 manufactured by Kureha Chemical Industry Co., Ltd.
sJ(7)) was inserted into the screw along with polypropylene pellets, and fed under tension at a rate of 2 kg/hour. At this time, the pressure of the die head is lOO~1
Although the extrusion rate increased to 68 kg/ctn', extrusion was carried out smoothly, and carbon fiber-containing resin pellets containing chopped fibers were obtained at a rate of 10 kg/hour. Carbon in pellets! i was uniformly dispersed and mixed, and its average length was about 2.5+s layers.

(Example 2) Using an inflation filtration molding device equipped with a 25 mm single-screw extruder (manufactured by Jujuki Co., Ltd.) equipped with a 75 m+eφ circular die, the molding machine was operated in the same manner as in Example 1 to directly form the extruder. , carbon tama with folded diameter of 18cm
A blown film was produced. At this time, the resin used is polyethylene rF-210 manufactured by Sumima Kagaku Kogyo Co., Ltd.
-6J was used, and the operation was carried out at a Gui temperature of 170°C. The carbon fibers in the film were uniformly dispersed and mixed, and the average length was about 3 layers.

(Example 3) (See Figure 1 (B)) Using an extruder manufactured by the Institute of Plastics Engineering, equipped with intermeshing type co-rotating twin screws (caliber 36 + si), Gouy temperature and barrel temperature 220 ° C. Rotation speed 90
From the hopper □ (first hopper) of the extruder at rp ■, polyethylene F210-6 manufactured by Sumima Kagaku Kogyo Co., Ltd.
Pellets were fed at a rate of 5.5 kg/hr. A tow of "carbon fiber rT101S" manufactured by Kureha Chemical Industry Co., Ltd. was inserted into the screw from the ventro (second hopper) of the same extruder, and was fed by allowing the screw to rotate. At this time, the motor load was 16A, and the pressure at the head was 40 kg/c. Carbon fiber-containing resin containing chopped fibers was smoothly extruded in the form of a strand through 4 holes (4 holes) attached to the die.

After the strands were cooled in a water tank, they were cut with a cutter to obtain cylindrical pellets with a length of 4 mm at a rate of 10.2 kg/hour. The carbon fibers in the pellets were uniformly dispersed and mixed, and their average length was about 3 mm.

[Effects of the Invention] As described above, according to the present invention, by supplying the carbon arm in the form of a tow or filament into a screw extruder together with a thermoplastic resin, a sizing agent can be used in one step. Without.

A carbon fiber-containing resin composite material in which chopped carbon fibers are uniformly dispersed can be obtained very easily.

[Brief explanation of the drawing]

FIGS. 1(A) and 1(B) are schematic cross-sectional views showing a method for producing carbon fiber-containing resin pellets according to the present invention. 1, , Screw extruder 2, 2', , *-, Bar 3. , , carbon m,
*4...''Rel 5, Thermoplastic resin 6, Screw 7, Heater 8, Dice 9, Strand 10, Water tank

Claims (1)

[Claims] (1) Thermoplastic resin is supplied to the hopper mouth of a screw type extruder whose extrusion outlet temperature is kept above the melting temperature of the thermoplastic resin, and the thermoplastic resin is supplied from the hopper mouth or a second hopper mouth provided further downstream. Carbon fiber tow or filament yarn is fed into the barrel so as to be bitten by a screw, and while the carbon fiber is cut into chops by the rotation of the screw in the extruder barrel, it is mixed with resin, compounded, and extruded. A method for producing a carbon fiber-containing resin composite material.