JPS5953291B2 - Kneading method of thermoplastic resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently kneading a thermoplastic resin and a filler.

More specifically, the present invention relates to an improved method for homogeneously and efficiently kneading a thermoplastic resin and a filler using a conventional batch kneader such as a Banbury mixer or an intermix. When manufacturing various molded products using thermoplastic resin as a material, fillers are often added for the purpose of improving mechanical strength and chemical properties. When this blending is performed using a batch-type kneading machine such as a Banbury mixer or an Intermix, a predetermined amount of the ingredients are put into the kneading machine, and then the upper lid called a float is lowered and closed, and the rotor rotates. This is done by gelling the thermoplastic resin using shear force and heat from the jacket, and forcibly kneading the filler into the gel. However, in general, fillers, especially powders, are finer particles than thermoplastic resins and are more likely to scatter. , they tend to escape out of the kneading zone through the gap between the float and the jacket.As a result, the amount of material to be kneaded is insufficient in the kneading zone, and the rotor's action is not fully exerted, resulting in long processing times. This causes a decrease in time and throughput.To overcome these drawbacks, after the material is introduced into the kneader, the float is repeatedly moved up and down until gelation begins. It is common practice to mix the filler while returning it to the kneading area, but this method is complicated and less effective, and in addition, the filler turns into dust when the float is moved up and down. However, this is not satisfactory as it causes undesirable results such as contamination of impurities.On the other hand, in order to promote gelation and improve productivity, the jacket of the kneading machine is heated to a temperature higher than the gelation temperature of the resin. is also known to be effective.

In this case, the amount of heat required to gel the raw resin does not depend on the heat generated by the shear force of rotor rotation;
The heat is mainly supplied from the jacket, but since the heat from the rotor rotation is added at the same time as the heat from the jacket,
If the kneading time is too long, the resin will become overheated, resulting in deterioration and coloring of the resin, so there is a drawback that various additional equipment must be prepared to prevent this. In addition to the operational disadvantages due to mechanical causes as described above, it is also possible to avoid deterioration in product quality due to component separation and non-homogenization due to the difference in specific gravity between the thermoplastic resin and filler in the material. There is also the disadvantage that this tendency increases as the filler content increases.

Therefore, the development of a method that can homogeneously and efficiently knead thermoplastic resin and filler using a conventional batch-type kneader to obtain a blend of consistent quality is an area of interest in this technical field. This has become an important issue in Japan.

As a result of intensive research to solve these problems, the present inventors found that by adding a certain kind of powder dispersing agent, the dispersion state of the thermoplastic resin and filler can be maintained well. It has been discovered that, while uniform kneading is achieved, it is possible to completely prevent the filler from escaping from the kneading zone and to shorten the processing time, and based on this knowledge, the present invention has been accomplished.

That is, when kneading a thermoplastic resin and a filler using a batch-type kneader, a mixture consisting of 20 to (1)% by weight of the thermoplastic resin and 80 to 20% by weight of the filler: 4==mon=oxshideon The object of the present invention is to provide a kneading method characterized in that the kneading process is carried out while adding and applying shear force.

In the method of the present invention, it is necessary to add polyfluoroethylene that can be fifurylized as a powder dispersing agent to homogeneously disperse the thermoplastic resin and filler.

This polyfluoroethylene that can be fifurlylated is polyfluoroethylene that can be fifurlylated by applying compression and shearing, and it can be obtained by dispersion obtained by emulsion polymerization of tetrafluoroethylene or by separating and granulating it. Fine powder for paste extrusion obtained by These fifurylizable polyfluoroethylenes are available in dispersions as about 60% aqueous colloidal suspensions of particles with an average particle size of about 0.2 microns and as fine powders with an average particle size of about 0.2 microns.
It is readily available as a powder with an average particle diameter of about 0.5 mm, which is agglomerated micron primary particles. Particularly suitable fines) include Teflon 6J and 6JC (registered trademarks; manufactured by Mitsui Urochemical Co., Ltd.), Polyflon F-103 and F-201 (registered trademarks,
Dispersions include Polyflon D-1 and D-2 (registered trademark, manufactured by Daikin Industries, Ltd.), Teflon 30-J (registered trademark, manufactured by Mitsui Flochemical Co., Ltd.), etc. be able to. These fifurylizable polyfluoroethylenes contain 0.0 parts by weight of the thermoplastic resin and filler blend.
It is necessary to add it in a proportion ranging from 1 to 5 parts by weight.

If this amount is less than 0.01 part by weight, a sufficient powder dispersion effect cannot be obtained, and if it exceeds 5 parts by weight, adverse effects such as a decrease in product strength and processability will be observed. In general, the amount of polyfluoroethylene that can be fifuryled must be increased as the blending ratio of the filler is higher and the particle size or bulk specific gravity of the filler is smaller, and it must be decreased as the jacket temperature of the kneading machine is increased. can do.

Thermoplastic resins which are one component in the feedstock of the process of the invention include, for example, low density polyethylene, 7 high density polyethylene, polypropylene, polystyrene, polyamide, polyester, polycarbonate, ABS resin and the like. These may be used alone or in combination of two or more. There are no particular restrictions on the shape of the product, and it may be in the form of pellets, granules, or powder. In addition, the other component of the feedstock, the filling
Examples of agents include white carbon, magnesium carbonate, calcium carbonate, calcium sulfate, calcium sulfite, barium sulfate, aluminum hydroxide, talc, mica, kaolin, coconut flour, wood flour, glass powder, and other extenders for thermoplastic resins. In addition to the inorganic and organic powders commonly used as reinforcing agents, metal powders such as iron powder, aluminum powder, and zinc powder, and metal oxides such as iron oxide powder, alumina powder, magnesium oxide, and titanium oxide can also be used. can.

These are usually used as powders with a particle size of 0.01 to 50 microns). The blending ratio of these thermoplastic resins and fillers can be selected within the range of 20 to 80% by weight of the thermoplastic resin and 80 to 20% by weight of the filler.

If the amount of filler is smaller than this, the effect of adding the filler will be insufficient, and if this amount is used, it will not be possible to mix the filler easily without using a powder dispersant. Therefore, it is not necessary to use the method of the present invention. On the other hand, if the amount of filler exceeds 80% by weight, even if a powder dispersing agent is used in combination, the load on the rotor will be large, the motor will be likely to be overloaded, and it will be difficult to obtain a homogeneous kneaded product. However, with conventional kneading methods such as methods using intermix, it was impossible to increase the amount of filler blended to 70% by weight or more, but with the method of the present invention, the upper limit can be increased to 80% by weight.
The fact that we were able to raise the temperature to this level has extremely important technical significance.

In the method of the present invention, a mixture of a thermoplastic resin and a filler is used as a raw material, and if desired, a fibrous reinforcing material such as glass fiber or asbestos fiber, a pigment, an antistatic agent, a lubricant, an antioxidant, It is also possible to use one to which conventional components such as an ultraviolet absorber and a coupling agent are added.

When carrying out the method of the present invention, the thermoplastic resin, the filler, and the fibrillatable polyfluoroethylene may be fed simultaneously to a kneader, or a premixer may be used in advance to feed both the thermoplastic resin and the filler. Alternatively, after heating and mixing polyfluoroethylene which can be fibrillated with either one of them, the mixture may be supplied to a kneader.

This premixing method is particularly advantageous when fibrillatable polyfluoroethylene in dispersion form is used. The method of the present invention can be carried out using any mixing method as described above, but in either case, it is necessary to apply shear force to fibrillate the polyfluoroethylene.

This fibrillation is normally carried out by shearing and force generated by the rotation of the rotor of a kneader, and there is no need for any special operation. The polyfluoroethylene fibrillated in this way plays the role of trapping the filler powder and homogeneously dispersing it in the thermoplastic resin, and also suppresses the separation of each component and the escape of the filler from the mixing zone. do. According to the method of the present invention, the working efficiency of conventional batch kneaders can be significantly improved, and a homogeneous kneaded product with constant quality can be obtained in a short time.

The method of the present invention also has the advantage of making it possible to incorporate a large amount of filler into the thermoplastic resin, which was not possible with conventional methods. Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Pellet-like high-density polyethylene (MI 0.4, density 0.
962, melting point 134°C), 64 parts by weight of heavy calcium carbonate (average particle size 4 microns), and 1 part by weight of calcium stearate, Teflon 6J (fine powder for paste extrusion, Mitsui Fluorochemical Co., Ltd.) Seven types of samples were prepared, including one without the addition of different amounts of the following products:

Next, these samples were kneaded using a 701-Bamburi mixer (manufactured by Kobe Steel, Model 111), and this kneaded product was mixed with 2
The mixture was fed onto a 24-inch roll and kneaded for an additional 3 minutes, then fed to an 18-inch inverted L-shaped calender and formed into a sheet with a thickness of 0.2 mm.

The operating conditions at this time were as follows. A Banbri mixer kneading conditions casing temperature
150℃Supplied material temperature 25℃Material charge amount 85kg/batch Material removal temperature
180℃ B two roll kneading conditions Roll temperature 150℃ Roll rotation speed 33rpm, 38rpm Roll gap
5mmC calendar molding conditions first,
Second and third roll temperature 175℃ Fourth roll temperature
150℃ takeoff roll temperature
105° C. Fourth roll peripheral speed 25 m/min During kneading with a Banbury mixer, processing conditions during calendar molding and product performance of the obtained sheet were observed and measured, and the results are shown in Table 1.

Example 2S Pellet-like polypropylene (isotactic homopolymer, MIO.6, density 0.90, Vikat softening point 14)
5°C) and talc (average particle size 8 microns) at various blending ratios to prepare eight types of samples, and for each sample, poly. Freon F-103 (
Fine powder for paste extrusion, manufactured by Daikin Industries)
The state of crosstalk was investigated with and without the addition of 0.5 parts by weight.

The kneading machine used was 31-Intermix (4) manufactured by Tatsutaura, model K-1) under the conditions shown below. did.

Casing temperature: 120°C Feeding material temperature: 25°C The amount occupying the volume of 31 after kneading the material was calculated from the blending ratio and true specific gravity of the materials. Material removal temperature: 200°C Rotor rotation speed: 50 rpm Obtained in this way Using a press molding machine heated to 200°C, the kneaded mixture was formed into a film with a thickness of about 0.1wn.
- The dispersion state of the filler was observed and the results are shown in Table 2.

Claims (1)

[Claims] 1 When kneading a thermoplastic resin and a filler using a batch-type kneader, the 10%
A kneading method characterized by adding polyfluoroethylene that can be fibrillated at a ratio of 0.01 to 5 parts by weight per 0 parts by weight, and kneading while applying shear force.