WO2018028196A1

WO2018028196A1 - Continuous rubber mixing process method

Info

Publication number: WO2018028196A1
Application number: PCT/CN2017/076418
Authority: WO
Inventors: 汪传生; 朱琳; 刘营; 边慧光
Original assignee: 青岛科技大学
Priority date: 2016-08-12
Filing date: 2017-03-13
Publication date: 2018-02-15
Also published as: CN106273022A; CN106273022B

Abstract

A continuous rubber mixing process method comprising a first step of continuous mixing: part of a weighed raw rubber raw material in a formulation and each of other systems in the formulation are added into an internal mixer for mixing; after being mixed for a predetermined time, the rubber material directly enters a counter-rotating twin-screw extruder for extrusion; and the extruded rubber material directly enters a double-roll tablet press for tablet pressing forming to obtain a pre-dispersion rubber master batch; a second step of continuous plastication: the remaining part of the raw rubber raw material in the formulation is added into a continuous plasticator (5) for plastication to obtain a plasticated rubber; and a third step of continuous mixing: the pre-dispersion rubber master batch and the plasticated rubber are continuously and quantitatively added into a continuous mixer (7) for continuous mixing. Sulphur stays for a short time and has a low temperature in the internal mixer so no scorching will occur; the produced rubber is homogeneous and high in quality; the production is continuous; and the production efficiency is high.

Description

Continuous rubber mixing process method

Technical field

The invention relates to the technical field of rubber processing, in particular to a continuous rubber mixing process method.

Background technique

The rubber industry is one of the important basic industries of the national economy. It not only provides people with light-duty rubber products such as daily use and medical products that are indispensable for daily life, but also provides heavy industries and emerging industries such as mining, transportation, construction, machinery and electronics. Various rubber production equipment or rubber parts, and the quality of the mixing technology plays a decisive role in the quality of rubber processed products. Therefore, the production of low-energy, high-efficiency, high-quality rubber is an ongoing problem in the rubber industry.

The traditional rubber mixing method can not achieve large-scale continuous production. If large-scale continuous production is to be realized, it is necessary to equip multiple sets of the same type of mixer or open mill, provide large-area parking warehouse, and the overall production line is too long and time consuming. More, and multiple operation steps need to be completed manually, resulting in low efficiency.

The traditional mixing method is to add sulfur to the mill, because the difference in human rubber mixing technology makes the quality of the rubber compound unstable, the unsafe factors increase, and the traditional mixing process is easy to cause early sulfur.

There are a number of improvements in the rubber compounding process in the prior art. For example, in Chinese Patent Application No. 201510405481.9, a fully automatic continuous rubber mixing method for a cable factory is disclosed, in which the vulcanization system is continuously mixed. The addition of the second section of the refining machine has not completely solved the problem of early sulfur.

For example, Chinese Patent Application No. 201410648268.6 discloses a tandem type rubber continuous kneading method in which, when kneading is carried out in an internal mixer, it is first added to an internal mixer for mastication, and then sulfur and The compounding agent other than the accelerator is kneaded. The above mixing method is only for The improvement made by the conventional rubber mixing process can not solve the sulfur problem well, and the continuous mixing is not fully realized.

Summary of the invention

In view of the above technical problems in the related art, the present invention proposes a continuous rubber compounding process method, which can not only realize continuous rubber compounding production, but also produce a rubber compound which does not have early sulfur and has excellent performance in all aspects.

To achieve the above technical purpose, the technical solution of the present invention is implemented as follows:

A continuous rubber mixing process comprises a continuous mixing section, a continuous mastication two-stage and a continuous mixing three-stage, and the continuous mixing step comprises: part of the raw rubber raw material in the weighed formula And other systems in the formula are added to the internal mixer for mixing; after the predetermined time of mixing, the rubber directly enters the counter-rotating twin-screw extruder for extrusion; the extruded rubber directly enters the double-rolling tablet Press molding in the machine to obtain pre-dispersed masterbatch;

The two steps of the continuous mastication process comprises: adding the remaining part of the raw rubber raw material in the formula to a continuous plasticizer for mastication to obtain a plasticating rubber;

The three-stage continuous mixing step comprises: continuously and quantitatively adding the pre-dispersed masterbatch and the plasticating compound to a continuous mixer to obtain a rubber compound.

Further, the rubber is discharged and cooled after the continuous three-stage mixing.

Further, in the continuous mixing step, the raw rubber raw material is 1/4 of the raw rubber raw material in the formula, and the raw rubber raw material in the continuous plasticating two-step step is 3/4 of the raw rubber raw material in the formula.

Further, the ratio of the pre-dispersed masterbatch and the plasticating compound in the three-step continuous mixing process is controlled by the screw rotation speed of the twin-screw extruder, the roller rotation speed of the double-roll tablet press, and continuous mastication. The ratio of the screw speed of the machine is 1:1:1.

Preferably, the process parameters of the continuous mixing section of the intermediate mixer are: 70% filling coefficient, rotor speed 60±15r/min, temperature control 50±10° C., top plug pressure 0.6±0.05 MPa, mixing Time 1 min; the screw speed of the twin-screw extruder was 25 rpm; the roller speed of the twin-roll tablet press was 25 rpm.

Preferably, the continuous kneading machine rotor speed is 25 rpm in the continuous mixing three-step process, the feeding section barrel temperature control temperature is 95 ° C, the mixing section barrel temperature control temperature is 85 ° C, the extrusion section barrel The temperature control temperature was 75 ° C, and the cooling channel temperature inside the mixer head was 65 ° C.

Further, in the step of continuously mixing, a mixing and extrusion molding machine is used, wherein an internal mixer is disposed above the counter-rotating twin-screw extruder, and the discharge port of the internal mixer corresponds to a feed port of the counter-rotating twin-screw extruder; the double-roll tablet press replaces the head of the counter-rotating twin-screw extruder, and the discharge port of the counter-rotating twin-screw extruder corresponds to The inlet of the two-roll tablet press.

Preferably, the weighing in the continuous mixing step adopts an automatic weighing device, and is disposed in the front section of the internal mixer, and weigh the raw rubber raw materials, small materials, carbon black and vulcanization system in the formula, respectively. After weighing, it is added to the internal mixer.

Further, the pre-dispersed masterbatch and the plasticating compound in the three-step continuous mixing step are continuously and quantitatively added to the continuous mixer for continuous mixing by means of conveyor belt transportation.

Preferably, the pre-dispersed masterbatch is discharged onto the conveyor belt by a two-roll tableting machine; the plasticating rubber is discharged onto the conveyor belt through the discharge port of the continuous plasticizer, and the conveyor belt is positively reversed by motor control. The compound is periodically delivered to the continuous mixer.

The invention has the beneficial effects that the sulfur in the process has short time in the internal mixer, low temperature, no early sulfur, uniform glue produced, high quality, continuous production, high production efficiency and compact structure between the devices. The overall device has a small footprint and low investment cost.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings to be used in the embodiments will be briefly described below. Obviously, the drawings in the following description are only some of the present invention. For the embodiments, those skilled in the art can obtain other drawings according to the drawings without any creative work.

1 is a schematic view showing a process flow of a continuous rubber compounding method according to an embodiment of the present invention;

2 is a schematic structural view of a continuous rubber mixing device according to an embodiment of the present invention;

Figure 3 is a front elevational view of the continuous mixer in accordance with an embodiment of the present invention;

4 is a plan view of a continuous mixer according to an embodiment of the present invention;

5 is a schematic diagram showing a tensile strength comparison column in a rubber material performance comparison experiment according to an embodiment of the present invention;

6 is a schematic diagram showing a comparison of tear strength in a comparison test of a rubber compound according to an embodiment of the present invention;

Fig. 7 is a schematic view showing the comparison of the dispersion degree of carbon black in the performance comparison experiment of the rubber compound according to the embodiment of the present invention.

In the picture:

1, automatic weighing system; 2, the mixing part; 3, twin-screw extrusion part; 4, double-rolling tableting head; 5, continuous plastic machine; 6, conveyor belt; 7, continuous mixing machine.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention are within the scope of the present invention.

As shown in FIG. 1 , a continuous rubber mixing process method according to an embodiment of the invention includes the following steps:

(1) Preparation of masterbatch: Weigh the small material, carbon black and vulcanization system through the automatic weighing system, and add all the small materials, carbon black, vulcanization system and 1/4 of the glue to the mixing part, and cut Mixing for 1 minute; the temperature during the mixing process is not more than 100 ° C, the uniformly mixed rubber is discharged through the outlet of the mixing section to the inlet of the twin-screw extrusion section, and the twin-screw is rotated in the opposite direction to feed the rubber. Enhanced shear joint solution, compared with co-rotating twin-screw extruder, high-efficiency, exhaust effect and melting efficiency of the counter-rotating twin-screw extruder The product is better; the rubber compound after the kneading and kneading is pressed through the discharge port of the twin-screw extruding portion through the double-rolling tableting head to obtain the masterbatch. The two-roller tableting head feeds the masterbatch to the feed port of the continuous mixer through a conveyor belt to achieve continuous feeding of the continuous mixer.

The working parameters of the mixing part are: 70% filling factor, rotor speed 60±15r/min, temperature control 50±10°C, upper plug pressure 0.6±0.05MPa; twin screw extrusion part rotor speed 25rpm The speed of the double roll tableting head was 25 rpm.

(2) Mastication: The remaining 3/4 of the glue is added to the continuous plasticizer for mastication; the ratio of the masterbatch to the remaining glue is controlled by controlling the rotation speed of the twin-screw extruder and the continuous plasticizer. The speed of the continuous plasticizer was 25 rpm.

(3) Transportation: The mother rubber is discharged onto the conveyor belt through the double-rolling tableting machine head. The plasticized rubber is discharged to the conveyor belt through the discharge port of the continuous plastic mixer, and the conveyor belt is positively reversed by the motor control. The compound is periodically delivered to a continuous mixer.

(4) Kneading: 3/4 of the glue which was masticated in the continuous plasticizer and the masterbatch which was pressed by the two-roll tablet press were conveyed to a continuous kneader for kneading. The continuous mixer rotor speed is 25 rpm, the feeding section barrel temperature control temperature is 95 ° C, the mixing section barrel temperature control temperature is 85 ° C, the extrusion section barrel temperature control temperature is 75 ° C, the mixer head The internal cooling channel temperature is 65 °C.

(5) Filming and cooling: The continuous mixer completes the compounding of the rubber compound by adjusting its rotor speed and temperature control system. During the mixing, the temperature of the rubber compound in the continuous mixer is controlled to be no more than 100 °C to prevent glue. The vulcanization of the material; the rubber compound after the kneading is passed through the extrusion section of the continuous kneader to realize the filming of the rubber; the rubber compound produced by the continuous kneading machine is cooled and folded by the film post-processing device to form a film storage. use.

The continuous rubber mixing process in this embodiment is specifically carried out in a continuous rubber mixing device, as shown in FIGS. 2-4, the main structure of the device includes a small material weighing system 1, a mixing portion 2, and a twin screw extrusion. a portion 3, a double roll tableting head 4, a continuous plasticizer 5, a conveyor belt 6, a continuous mixer 7, and a feed port of the twin-screw extruding portion 3 below the discharge port of the mixing portion 2, To realize continuous feeding; the head of the twin-screw extruding part 3 is directly connected to the double-rolling tableting head 4, and the double-rolling tableting head 4 is docked with the feeding port of the upper end of the continuous mixing machine 7 through the conveyor belt 6 to continuously mold The head of the refiner 5 passes the conveyor belt 6 Docking with the feed port at the upper end of the continuous mixer.

(1) In the present invention, a continuous mixing section is carried out, using a continuous internal mixer, including the uppermost small material weighing system, as a mixing part of the main body, a twin-screw extruding part below and a machine head Double roll tableting head.

In the present invention, the weighing and conveying of the raw materials in the formula is carried out by a small-weighing weighing system for manual weighing or by computer-controlled automatic weighing. The small material weighing system includes carbon black automatic weighing and conveying system, oil automatic weighing and conveying system, vulcanizing system automatic weighing and conveying system and raw rubber automatic weighing and conveying system.

The continuous mixer combines the excellent mixing characteristics of the internal mixer with the continuous operation of the twin-screw extruder. With the multiple action of the rotor screw and the mixing chamber, the material is subjected to strong extrusion, shearing and mixing. The material is dissipated in the material at a very fast rate in a very short time, so its shear mixing is very strong. For materials with high dispersion mixing, the intense mixing is accompanied by high shear stress, resulting in rapid fragmentation and uniform dispersion of the gel particles and the mass in the polymer.

(2) In the present invention, the raw rubber (natural rubber in the examples) is subjected to mastication by a continuous plasticizer. The principle of mastication by mechanical force is: under the action of mechanical force, the rubber macromolecular chain is first cut at high temperature to generate macromolecular radicals. If there is oxygen around, the generated free radical will immediately react with oxygen to form rubber macromolecular hydrogen peroxide. This will prevent the recombination of rubber radicals and play the role of mastication. When the temperature is high, the rubber is softened, the mechanical force is significantly reduced, the oxygen on the surface of the rubber is activated, and the rubber macromolecule is oxidatively fractured to complete the mastication.

The mastication process is a process in which the rubber macromolecular chain is broken and the molecular chain is shortened to make the molecular weight distribution uniform. There are two main factors that cause macromolecular chain breakage during the mastication process: one is mechanical destruction; the other is thermal oxidative degradation. At low temperature mastication, the macromolecules are broken under strong mechanical force due to mechanical damage. Thermal oxidative degradation dominates during high temperature mastication.

The mechanical shearing force and high-temperature heat between the screw and the barrel of the screw-type plasticizer are used to break the rubber molecular chain, and the difference from the mastication of the open mill and the mixer is the effect of oxygen on the raw rubber in the screw mastication method. Smaller. When using a screw plastic mixer, the temperature of the glue should be strictly controlled below 180 °C, and take care to prevent the glue. After the surface of the rubber compound oxidation, try to avoid the formation of raw rubber.

The rubber continuous masticating equipment includes a main machine, a feeding mechanism, a heating and cooling system and a control system. The control system is connected to the heating and cooling system, the transmission system and the feeding system to realize intelligent monitoring of the operation process of the plastic mixer.

The rubber continuous plasticizer adopts a combined parallel double rotor structure, and the two rotors rotate inward, and each rotor is sequentially mounted on the mandrel in phase and order by various components for feeding, masticating, conveying and extruding functions. The modular structure of the building blocks is easy to manufacture, install, and maintain, and the mastication effect can be improved by changing the type or position of the components. Continuous plastic mixer uses a variety of plastic rotor components such as kneading block, meshing type dense rotor, shear type dense rotor, pin barrel, hexagonal prism, large lead, toothed disc, etc. Shearing, stretching, tearing and squeezing, the rubber macromolecular chain is broken, and macromolecular radicals are generated to obtain a sufficient and uniform mastication effect.

Therefore, in the present invention, a continuous plasticizer is used as the second section of the continuous mastication, and low-temperature mastication is adopted to reduce the molecular weight and viscosity of the raw rubber to improve the plasticity thereof, and to obtain appropriate fluidity to satisfy the further processing of the mixing and molding. need.

(3) In the present invention, the continuous mixing three-stage is a continuous kneading machine, and the continuous kneading machine rotor is composed of two rotors of the same size and symmetrical structure. During the operation of the counter-rotating double-rotor continuous mixer, the two rotors rotate in an anisotropic, equal-speed and partially meshed state to achieve a comprehensive function of feeding, shearing, kneading, conveying, mixing and extrusion. As shown in Figure 3-4.

The main structure of the barrel of the continuous kneading machine comprises a four-stage structure and a barrel of the same size. Each barrel has a circular groove for installing the mixer rotor, and the inner wall of each barrel is cooled. The channel is used to control the temperature of the mixer barrel, and the four-stage barrels are sealed and docked by bolts.

Wherein, the feed port is opened directly above the rightmost barrel, and a thick layer is arranged at the edge of the feeding port to prevent the cooling passage from penetrating through the bolt and the hopper, and the continuous internal mixer and the continuous masticating The rubber obtained by the machine is transported to the top of the feed port through a conveyor belt for feeding.

The inside of the mixer head is provided with a cooling passage for controlling the temperature of the head of the mixer, and the joint between the mixer head and the mixer barrel is fixed by bolts, and the water can be selected as needed in the cooling passage. Or different cooling media such as oil.

Example

The formula adopted in this embodiment is a full steel radial tire tread rubber formula, and the mixing method adopts the continuous rubber mixing process method of the present invention, wherein the specific formula table is as follows:

Comparative example

In the present invention, a conventional continuous mixing process is adopted as a comparison, and specific steps include:

(1) Using a filling factor of 65±3%, based on the specific model of the internal mixer and the production formula of the rubber mixture described in the examples, calculate the mass of each material and weigh it after use, setting the density. The working parameters of the mixer adopt 70% filling coefficient, the rotor speed is 60±15r/min, the temperature control is 50±10°C, and the upper plug pressure is 0.6±0.05MPa;

(2) The natural rubber weighed in step (1) is put into an internal mixer for 35±3s mastication, and then carbon black N330, zinc oxide, antioxidant RD, plasticizer A, stearic acid are separately added. SA is mixed; when the temperature of the rubber compound in the mixing chamber reaches 110±3°C and 120±3°C, each rise and fall of the top plug is made once, so that the rubber compound is fully mixed, when it is in the mixing chamber. The temperature of the rubber compound rubber reaches 140±3°C, and the mixing is completed to open the lower plug to discharge the rubber;

(3) After the discharged rubber compound is subjected to a plurality of tableting by the open mill of the prior art, the accelerator NOBS and sulfur are added to the formulation to be thoroughly mixed by means of a triangular package, and then subjected to subsequent Related processes and test comparisons.

5 is a schematic diagram showing a tensile strength comparison column of a continuous rubber mixing process and a conventional internal mixer mixing method for producing five sets of rubber materials, wherein the horizontal axis represents the sample number. For the first group, the second group, the third group, the fourth group and the fifth group, the vertical axis represents the tensile strength / MPa, the black column represents the conventional internal mixer mixing method, and the gray column represents the continuous rubber mixing of the present invention. Refining process.

6 is a schematic diagram showing a comparison of a tear strength corresponding to a continuous rubber mixing process and a conventional internal mixer mixing method for producing five sets of rubber materials, wherein the horizontal axis represents the sample number divided into the first group, the first Group 2, Group 3, Group 4 and Group 5, the vertical axis represents the tear strength KN/m, the black column represents the conventional internal mixer mixing method, and the gray column represents the continuous rubber compounding process of the present invention.

7 is a schematic diagram showing a comparison of carbon black dispersion degree corresponding to a continuous rubber mixing process method and a conventional internal mixer mixing method according to the present invention, wherein the horizontal axis represents the sample number is divided into the first group, Group 2, Group 3, Group 4, and Group 5, the vertical axis represents carbon black dispersion, the black column represents a conventional internal mixer mixing method, and the gray column represents the continuous rubber compounding process of the present invention.

It can be seen from Figures 5-7 that the performance of the rubber compound produced by the continuous rubber compounding process of the present invention is much higher than that of the conventional rubber compounding process.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., which are included in the spirit and scope of the present invention, should be included in the present invention. Within the scope of protection.

Claims

A continuous rubber mixing process method comprises a continuous mixing section, a continuous plasticizing two-stage and a continuous mixing three-stage, wherein

The step of continuously mixing comprises: adding a part of the raw rubber raw material in the weighed formula and other systems in the formula to the internal mixer for mixing; after the predetermined time of mixing, the rubber material directly enters the opposite direction. Extrusion is carried out in a twin-screw extruder; the extruded rubber is directly introduced into a two-roll tablet press for tableting to obtain a pre-dispersed masterbatch;

The two steps of the continuous mastication process comprises: adding the remaining part of the raw rubber raw material in the formula to a continuous plasticizer for mastication to obtain a plasticating rubber;

The three-stage continuous mixing step comprises: continuously and quantitatively adding the pre-dispersed masterbatch and the plasticating compound to a continuous mixer to obtain a rubber compound.
The continuous rubber compounding process according to claim 1, wherein the rubber is subjected to sheeting and cooling after the continuous three-stage mixing.
The continuous rubber compounding process according to claim 1, wherein the raw rubber raw material in the continuous mixing step is 1/4 of the raw rubber raw material in the formula, and the continuous plasticating two-stage step The raw rubber raw material is 3/4 of the raw rubber raw material in the formula.
The continuous rubber compounding process according to claim 1, wherein the ratio of the pre-dispersed masterbatch and the plasticating compound in the three-step continuous mixing step is controlled by a twin-screw extruder The ratio of the screw speed, the roller speed of the two-roll tablet press, and the screw speed of the continuous plasticizer was 1:1:1.
The continuous rubber mixing process according to claim 4, wherein the process parameters of the continuous mixing section of the intermediate mixer are: 70% filling factor, rotor speed 60±15r/min, temperature control is 50±10°C, the top plug pressure is 0.6±0.05MPa, the mixing time is 1min; the screw speed of the twin-screw extruder is 25rpm; the roller speed of the double-roll tablet press is 25rpm.
The continuous rubber compounding process according to claim 5, wherein the continuous kneading machine rotor rotation speed is 25 rpm in the continuous mixing three-step process, and the feeding section barrel temperature control temperature is 95 ° C, mixed The temperature control temperature of the refining barrel is 85 °C, the temperature control temperature of the barrel of the extrusion section is 75 °C, and the cooling channel temperature inside the head of the mixer is 65 °C.
The continuous rubber compounding process according to claim 1, wherein a step of the continuous kneading adopts a kneading extrusion molding machine, wherein the internal mixer is disposed on the counter-rotating twin screw Above the extruder, the discharge port of the internal mixer corresponds to the feed port of the counter-rotating twin-screw extruder; the double-roll tablet press replaces the head of the counter-rotating twin-screw extruder The discharge port of the counter-rotating twin-screw extruder corresponds to the inlet of the two-roll tablet press.
The continuous rubber mixing process according to claim 7, wherein the weighing in the continuous mixing step is performed by an automatic weighing device, and is disposed in the front section of the internal mixer, and weighed separately. The raw rubber raw materials, small materials, carbon black and vulcanization system in the formula are weighed and added to the internal mixer.
The continuous rubber compounding process according to claim 1, wherein the pre-dispersed masterbatch and the plasticating compound in the three-step continuous mixing step are continuously and quantitatively added to the continuous mixing by means of conveyor belt transportation. Continuous mixing in the machine.
The continuous rubber compounding process according to claim 9, wherein the pre-dispersed masterbatch is discharged onto the conveyor belt by a two-roll tablet press; the plasticating rubber is discharged through a continuous plasticizer The mouth is discharged onto the conveyor belt, and the conveyor belt is positively reversed by motor control, and the rubber material is periodically conveyed to the continuous mixer.