JPS58887B2 - Kneading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called internal mixer, which is capable of sufficiently kneading materials regardless of their type.

An internal mixer is a batch type kneading machine that is suitable for mixing rubber and plastics, and is especially suitable for masticating rubber, mixing carbon master batches, or mixing vulcanizing agents, which is usually called professional mixing, for tire mixers. It is an indispensable mechanical equipment for the rubber industry such as manufacturing.

A conventional internal mixer includes a pair of parallel rotors 2 rotating in opposite directions in a chamber 1, as shown in FIGS.
. It's in the direction.

The material inputted from a hopper (not shown) is forced into the kneading chamber 7 through the supply port 10 by the biting action of the rotor and the pushing action of the floating grate. It passes while being crushed between the tip and the inner wall of the casing (chip clearance 6), and is sent in the axial direction of the rotor.

This action takes place on each of the long and short blades, which have opposite winding directions so that the material is transferred from the ends to the center for each rotor, and the kneaded material is removed from the lower part of the chamber.

Further, as shown in FIGS. 4 to 6, there is a so-called four-blade rotor in which each rotor has two long blades and two short blades, for a total of four blades.

This configuration has the same effect, but since it has twice the number of chips compared to a two-blade rotor, the microdispersion of additives is more advanced and the kneading efficiency is generally higher.

On the other hand, in order to obtain a homogeneous mixture, micro-dispersion is carried out, and the concentration of the added chemicals and additives is constant no matter which part of the kneaded material is taken, and the concentration of the kneaded material is kept constant. The so-called macro dispersion effect, which involves uniformly mixing the ingredients, is also important.

For example, if the vulcanizing agent is not mixed uniformly during the professional mixing process in the tire manufacturing industry, the physical properties of the final product will vary.
It becomes difficult to manufacture tires of consistent quality.

In particular, the proportion of recent tires that use steel radial tires, which have steel cords inside them, has been increasing in order to improve safety during high-speed driving. However, materials tend to be much harder and more difficult to mix and disperse uniformly.

For this reason, conventional ink-null mixers sometimes have problems such as insufficient strength of the kneading machine and insufficient uniform dispersion of chemicals.

In view of these points, the present invention focuses on the movement of materials in the mixer when kneading with an internal mixer, and aims to provide a kneading and kneading device that can perform macroscopically sufficient mixing regardless of the type of material. This is the purpose.

As shown in FIGS. 1 to 6, the rotor of the internal mixer has spiral blades to feed the material in the axial direction of the rotor.

Therefore, the movement of the material inside the kneading chamber is divided into a flow in the axial direction of the rotor and a flow between the left and right kneading chambers housing the rotor.

In order to obtain a uniform kneaded product, it is necessary to activate the flow in the axial direction and the flow between the kneading chambers, and to prevent material from stagnation in the kneading chambers.

Ink-null mixer with 4-blade rotor (inner volume 236
When professional kneading of hard rubber was carried out in 1), it was found that in some types of rubber, the dispersion of chemicals was extremely uneven, and that the uniform dispersion of additives was significantly inferior to that of the two-blade rotor.

In order to find out the reason for this, we created a model testing machine and observed the state of material flow inside the mixer.
The barrel of the model testing machine is made of acrylic resin, and has a structure that allows direct observation of the flow of material inside.

In addition, in order to quantitatively evaluate the quality of dispersion, a certain amount of colored plastic beads (polystyrene) was added.
After crosstalk, repeat the number of beads included in a certain sample.
times) and expressed as the variation in the number of beads (δn-1).

The model test machine has the same dimensions as an internal mixer with an internal volume of 1.7 tons, and a 30% aqueous solution of CMC (carboxy methyl cellulose) is suitable as a material that exhibits flow behavior similar to the hard rubber used in practical mixers. I discovered this and used it.

The results of kneading experiments of model substances using the two-blade rotor and four-blade rotor using the model testing machine described above are shown in Figure 7 (Iro), where A shows the beads when the kneading time is 40 seconds, and o shows the beads when the kneading time is 60 seconds. It shows the variation situation.

In the case of 2-blade rotor 11, compared to 4-blade rotor 12, the filling rate (volume ratio of material occupying between the kneading chambers) is 0.
．． The dispersion of beads is good over a wide range of 4 to 1.0, and uniform dispersion progresses even if the kneading time is short, but with a four-blade rotor, the higher the filling rate, the worse the dispersion becomes. Increasing the time does not improve the dispersion.

The reason why the four-blade rotor has such poor dispersion is that each rotor has two long blades and two short blades that are twisted in a direction that pushes the material toward the center. At the center where the short blades contact the blades, the tips of each blade are shifted in phase by 90 degrees as shown in Figure 6, and are arranged to improve the flow of material. After the material has left the end of the long blade, it does not have enough room to move to the other end of the mixer, and is forced back toward the long blade by the short blade, which is twisted in the opposite direction to the long blade. It became clear that the materials were pushed back and pressed together in the center of the rotor, resulting in a lack of axial flow of material necessary for uniform mixing.

On the other hand, in the case of a two-blade rotor, as shown in Figure 1, the ends of the long blades and the ends of the short blades are arranged so that they partially form a shape in the center of the rotor. The material flowed by the blades in the direction of the center of the rotor axis is released at the end of the long blade, flows into the space behind the short blade, and is swept back into the long blade section.

Therefore, the movement of the material itself is similar to that of a four-blade rake, but there is only one long blade and one short blade, so there is more space for the material to move, and the axial flow increases, resulting in uniform mixing of the kneaded material. It turned out that it was proceeding.

Regarding the non-uniform kneading caused by the insufficient flow of materials in the four-blade rotor, David, Z. Tyson, and others proposed in Japanese Patent Publication No. 42-27032.

That is, the cross-sectional shapes of the long blades and short blades are designed to reduce the bulge of the rotor at the ends near the center of the rotor and reduce the cross-sectional area, thereby improving the flow of the material and achieving uniform dispersion.

Therefore, the inventor of the present invention attempted to knead hard rubber using this method, but the method did not have a sufficient effect on hard rubber and yielded results that were unsatisfactory in practical terms.

Therefore, the present inventor developed a CM that behaves similar to hard rubber.
Using a C aqueous solution and making use of the high kneading efficiency of the four-blade rotor, we conducted various studies on the shape of the blades, and as a result, we found that the blade shape shown in FIG. 8 could be used.

That is, the pair of parallel rotors 2 and 3 are provided with long blades 4 and short blades 5, respectively, and these blades are formed in a spiral shape to feed the material in the axial direction, which is the same as in the conventional case. However, in this application, the winding direction of the spiral constitutes the long blades and short blades of each rotor in the same direction, and the flow direction along the axial direction of the material is in opposite directions between one rotor and the other rotor. It is set to be.

The axial cross-sectional shapes of the long wings and the short wings are uniform.

Furthermore, the ends of the long wings are not continuous with the short wings, and the two wings are out of phase with each other on the outer circumference of the loaf.

By making the flow direction of the long and short blades the same in this way, the material will not stay in the center and the axial flow will be promoted.
Since the other rotor causes the flow to flow in the opposite direction, the flow as a whole creates a large swirling flow.

That is, the material swept from one end of the rotor shaft to the center by the long blades is sent to the end of the long blades, where it is dissolved from the long blades and transferred to the short blades having a different phase.

This short wing also sends it in the same direction.

The material sent in the axial direction by the one rotor is axially transported in the opposite direction by the other rotor.

In this way, both rotors use a combination of long blades and short blades to transfer the material in the same direction in the axial direction, and because there is no push-back action to the center as in conventional rotors, the material is transferred in the axial center. There is no disadvantage of material retention,
Uniform mixing and dispersion is achieved throughout.

When kneading is performed using a device with this configuration, the ability to uniformly disperse plastic beads in a CMC aqueous solution is
As shown by curve 13 in the figure, it was shown that the dispersion was more uniform than that of a two-blade rotor, which is conventionally thought to have excellent dispersion ability.

Another feature is that it can be dispersed over a wide range of filling rates.

Furthermore, similar excellent results were obtained when the above configuration was applied to an actual mixer and professional kneading was performed by adding vulcanizing chemicals to hard rubber.

The kneading of vulcanizing chemicals is usually referred to as professional kneading, and it is necessary to keep the rubber temperature within a certain temperature range (for example, 110° C.) in order to prevent the vulcanization reaction of the chemicals during kneading.

Therefore, it is necessary that sufficient dispersion be achieved by kneading without causing a temperature rise.

In addition, if the purpose is simply to improve the swirling motion of the material in the kneading chamber, a continuous tool with continuous short blades and long blades as described in Japanese Utility Model Publication No. 49-43330, for example, may be used. However, it was found that this product was not suitable for professional kneading because the temperature of the rubber rose sharply when using a continuous tool.

Furthermore, by dividing the blades into long blades and short blades as in the present application, the thrust force that the rotor receives during kneading can be reduced to about half compared to the case of a continuous tool.

Example: In an internal mixer with an internal volume of 4.3 tons, there are two
We prototyped a rotor with long and short blades.

The ratio of the lengths of the short wings and long wings (Ls/Lt) is 0.49.
It is.

The rotation speed of the rotor was 40 RPM and compared with conventional standard two-blade and four-blade rotors.

The relationship between the rubber temperature and kneading time when a vulcanizing chemical is kneaded into hard rubber and the degree of dispersion of the chemical is shown in FIGS. 9 and 10.

In the figure, 14 indicates a two-blade standard rotor, 15 a four-blade standard rotor, and 16 a rotor according to the present invention.

The degree of drug dispersion is determined by variation, and the smaller the variation, the more uniformly the drug is dispersed.

As is clear from the figure, the rotor of the present invention allows additives to be uniformly dispersed even if the filling rate of the mixer is changed significantly, and when used for professional mixing, it is possible to easily disperse vulcanizing chemicals without raising the rubber temperature. uniform dispersion is possible.

As explained above, the present invention improves macro and micro kneading by improving the rotor blades, and is applicable not only to professional kneading but also to mastication, carbon masterbatch kneading, and other rubber kneading. It is also highly effective against crosstalk.

In addition, in the above embodiment, only an example of four blades was shown, but two
Of course, other numbers of wings may be used.

In addition, in this application, the above-mentioned Japanese Patent Publication No. 4
Unlike the rotor described in Japanese Patent No. 2-27032, there is no need to make the center part thinner, so there are advantages of excellent strength and durability.

[Brief explanation of the drawing]

Figure 1 is a plan view of the rotor of a conventional internal mixer.
2 and 3 are sectional views taken along lines ■-■ and I-I in FIG. 1, FIG. 4 is a plan view of another conventional rotor, and FIGS. -V line and ■-■ line cross-sectional view,
Fig. 7 is a comparative characteristic diagram of the mixed wire state by the present invention and the conventional device, Fig. 8 is a plan view of the rotor of the present invention, Fig. 9 is a relation diagram between kneading effect and temperature, and Fig. 10 is kneading effect. It is a relationship diagram between and kneading time. 2.3...Rotor, 4...Long blade, 5.
...Short wing, 6...Tip clearance,
13, 16...Characteristic curve of the present application.

Claims (1)

[Claims] 1 A kneading and kneading device in which a pair of parallel rollers rotating in opposite directions are arranged in a mixing chamber sealed by a casing and an end frame, each rotor having long blades and short blades. The blades extend spirally along the centerline of the rotor, and the long blades and short blades of each roller are formed with different phases, and the cross-sectional shape of each blade in the axial direction is uniform. The winding direction of the spiral is such that the long blades and short blades of each rotor are in the same direction, and the flow direction of the material to be kneaded along the rotor axis is opposite to each other in one rotor and the other rotor. A kneading device characterized by being set so that