JPH04503471A - Method for producing uniform finely separated particle mixture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Method for producing uniform finely separated particle mixture day The purpose of the invention is to form a homogeneous mixture.

The present invention relates to a method of mixing one or more different solid particulate materials.

More specifically, dispersion of fine particle aggregates and fine particle aggregates made of different materials 9. Then, while maintaining the homogeneity of the mixture, The present invention relates to a method for stabilizing. The stabilized mixture is then shaped, Processed by techniques such as extrusion and reaction to produce useful mixtures and composites. There is.

9-”1-JL-Niraichi In many industrial processes, finely separated particles consisting of one or more different materials Requires mixing or dispersion operations to obtain homogeneous mixtures or composites. this Such processes include, for example, compounding of rubbers, pigments for paints and plastics, etc. Production of filler pastes, and ceramic composites, especially like inorganic whiskers This includes the production process of materials reinforced with fibers. In most cases, the product properties are Uniformity of mixtures and aggregates and agglomerates down to individual final particles or monodisperse It is directly related to the degree of collapse.

Finely separated solid particles are subjected to various molecular, electrical and surface effect forces. There is a tendency for the particles to aggregate and form agglomerates due to the attraction forces between the particles. these The smaller the particle size, the greater the influence of the tethering force. For a few microns or less requires an acceleration several times the force of attraction to pull adjacent particles apart.

Examples of particulate materials commonly used in industry include carbon black, titanium oxide, Pigments such as zinc oxide, chalk, vulcanizing agents such as sulfur, ammonium nitrate and peroxide. Salts such as ammonium chlorate, such as polytetrafluoroethylene extruded powder Examples include plastics, finely divided metals and metal oxides. these grains The particle size of the material is usually several microns or less, and it is rare to obtain it in a monodispersed form. Ru. Instead, one must rely on physical operations to achieve the desired uniformity. The reality is that there is no such thing.

In the case of dispersing or mixing finely separated materials containing fine particle agglomerates, this agglomerate is A simple blend or They typically require more complex techniques than mixed techniques. high speed impeller Mixing devices equipped with such devices are generally not overnight effective. Normally, fine meshing brakes mixer with blades or a mixer with a small gap between the blades and the body. Adopts to generate strong mixing force and slow shear force to obtain intimate and homogeneous mixture It is necessary to adopt a device that allows Muller type mixer, pug mill, Ni mixers and other powerful mixers such as Banbury mixers may be used for this purpose. It is normal for this to occur.

Known means for obtaining homogeneous mixtures from fine particle agglomerates have a number of practical drawbacks. are doing. Significant local heating input required to obtain the desired degree of dispersion to occur. Localized heat generation associated with physical shearing forces is a cause of the deterioration of rubber and plastics. and lowers the average molecular weight. For heat-sensitive materials such as certain salts This can lead to decomposition and sometimes even lead to disaster. For reinforcing fibers with poor ductility In some cases, the shearing action substantially reduces the average aspect ratio of the fibers and therefore cannot be used effectively. I can't. Such as when making rubber and plastic compounds containing many fillers. However, if the mixture contains reactive components and catalysts, this local exotherm may This may lead to faster and more heterogeneous polymerization and reactions. Moreover, the residence time Generally, continuous processing is difficult or impossible, and batch processing is required. I am a connoisseur.

A method of compounding certain materials at low temperatures using refrigerants such as carbon dioxide or liquid nitrogen A law is proposed. U.S. Pat. No. 4,475,305 discloses that chemical reactivity Disclosed is a method of mixing liquids with granular solids to form a homogeneous mixture. Ru. In this case, solid freezing is performed by freezing a liquid to a temperature below its freezing point and separating it into fine pieces. forming particle aggregates, while freezing the solid particle aggregates below the freezing temperature of the liquid; . These materials are then mixed together and subjected to known solid-solid or liquid-solid mixes. Mix each other using a mixer while controlling the temperature so that the temperature does not exceed the freezing point of the liquid. Ru.

Canadian Pat. The proposal has been disclosed. According to this, a multicomponent system consisting of several naturally reactive components It describes how to prepare a chemical formulation, with each component being separated until the desired reaction occurs. Discloses a formulation that can maintain stability over a long period of time. References to such preparations In many epoxy resin formulations, the resin and hardener are frozen and separated. Grind into pieces in a refrigerant. The separate components are then intimately mixed in liquid nitrogen, resulting in 9 reactions. It can be stored indefinitely in its original state without being processed. When liquid nitrogen evaporates, it melts A reaction occurs. In the system described in this Canadian patent, during storage in liquid nitrogen, Separation of each component is possible when the specific gravity or density of each solid component is substantially the same. can only be avoided. French Patent No. 945.337 discloses that rubber at low temperatures The method for making the formulation is described. Cool the rubber to about -80℃ until it becomes brittle and turn it into powder. Grind into pieces. This rubber powder is mixed with other ingredients and the mixture is heated under pressure to Obtain the finished product.

Another proposal for mixing particulate solids at low temperatures is found in U.S. Patent Application No. 790.374. There is a description in .

One or more finely separated dissimilar materials, in which one or more of the is used when preparing a homogeneous mixture when two or more materials form an agglomerate of fine particles. All of the above-mentioned known methods suffer from serious drawbacks.

day Carbon black, inorganic compounds, rubber, plastics, vulcanizing agents and other finely separated from one or more different materials containing fine particle agglomerates such as A homogeneous mixture of separated solids is made into a slurry in which each component of the mixture is contained in liquid nitrogen. was prepared by forming. This slurry is then stirred and sheared with sufficient strength. Apply shearing force and continue stirring for a period of time until the agglomerates break down. A homogeneous mixture of individual particles resulting from fracture and particles from other materials is randomly mixed. one in suspension. This homogeneous suspension is then removed by removing liquid nitrogen. The stabilized mixture is then further extruded or molded into shaped products. . This method is particularly suitable for the production of filled rubber compounds and plastic compounds. It is also useful in the production of inorganic composites.

An object of the present invention is to provide a method for producing a homogeneous mixture of finely separated solid materials. be.

More specifically, it is an object of the present invention to produce aggregates or agglomerates of finely separated materials. disintegration to obtain a substantially monodisperse particle mixture, which is then further processed. The object of the present invention is to provide a method for stabilizing said mixture.

Still another object of the present invention is to prepare homogeneous mixtures of heat and shear sensitive materials for degradation and separation. The purpose is to provide a method to obtain the solution without having to solve it.

of t″U Figure 1 is for the preparation of filled plastics, rubber compounds, etc. Diagram of an embodiment for illustrating a particularly preferred batch to continuous process of the invention Figure 2 shows a rotor/fixture suitable for preparing a homogeneous mixture of granular materials. This is an explanatory diagram of a child-type disperser: Figure 3 is the result obtained by adopting the device shown in Figure 2. FIG. 3 is an explanatory diagram showing the flow of slurry and the collision pattern of particles; FIG. 4 is an explanatory diagram showing another embodiment of a part of the flow sheet of FIG. 1.

Day 1 0・ The present invention produces a homogeneous and substantially monodisperse mixture from finely separated lumpy solids. methods of preparing a compound and then stabilizing the mixture for further processing. Ru. Fine particles such as carbon black, fillers, pigments, salts, catalysts, etc. Homogenize separated bulk solids with other particulate materials such as rubber and other plastics. Concerning a method of mixing. In addition, in subsequent processing such as extrusion, casting, molding, pressing, etc. Stabilize the mixture so that it maintains its uniformity even after shaping into the desired shape. Regarding how to

Next, nine various embodiments of the present invention will be described in more detail with reference to the accompanying drawings. . Although generally described is a process for making a filled polymer or rubber composition, nine aspects of the present invention The techniques and methods are generally similar to many other systems, such as ceramic compositions. It should be understood that it can be applied similarly.

FIG. 1 shows a batch to continuous system 10 for obtaining a homogeneous mixture according to the present invention. Generally indicated. A slurry tank 11 is used to prepare each batch of the desired mixture. use This tank 11 has propeller blades driven by a motor 13. It is equipped with 12. Liquid nitrogen is supplied through conduit 14 into tank 11 to form a mixture. Use for minute slurry preparation.

The components constituting the mixture are usually solid at room temperature, but may also be liquid. solid One or more different types of granular solids are desired from the shaped material feed supply device 15. A fixed amount is supplied depending on the composition or prescription. This supply device 15 is.

One or more types of metering hopper discharged into the tank 11 by the transfer device 16 It consists of - In the present invention, certain plasticizers and prepolymers, such as Even materials that are liquid can be used in the same way as materials that are solid at room temperature. this place one or two types suitable for distributing a certain amount of material according to the batch requirements. The liquid feed device 17 equipped with the above measuring tank is used. to tank 11 It is appropriate to supply the liquid after charging the liquid nitrogen.

It is convenient to introduce this liquid substance into droplets through the nozzle 18; A conduit 19 communicates with the feed device 17 . The droplet from the nozzle 18 is 1 m long. Since it has a relatively small diameter of less than m, it will freeze soon if it falls into tank 11. . Frozen droplets behave like normal solid particulate materials. Another type of frozen liquid particles 1! ! ! The method involves injecting a stream of liquid components into liquid nitrogen in a tank 11 to create a mixer. 12, the particle stream is pulverized into particles having a particle size of 3 mm or less.

Several or more than 10 different materials can be contained in a single batch, with each Ingredients are added in predetermined amounts or ratios to ensure the same overall composition from batch to batch. It is possible to In the case of Gomuco formulations - natural rubber or Synthetic rubber, one or more vulcanizing agents such as sulfur, zinc oxide and stearic acid activators, reinforcing fillers like carbon black and filler pigments, fillers such as clay, accelerators, antioxidants, anti-ozonants, spreading agents, softeners, etc. Contains additives such as additives and other special purpose additives. These are all individual particles It is necessary to add it to the tank 11 in the form of particles with a diameter not exceeding several mm.

The ratio of particulate solids to liquid nitrogen and the agitation intensity of mixer 12 are determined depending on the solid material. Adjust to the extent that it can be maintained as a slurry without settling.

All ingredients constituting one batch are charged into tank 11 to form a slurry. After mixing, stream 21 is withdrawn from tank 11 through a dispersion and grinding device 30. . The device 30 applies a sufficiently strong stirring force and shearing force to this granular slurry to form lumps. disintegrates the particles and reduces the particle size of other particle aggregates to create a finely separated state. consisting of a device suitable for Figures 2 and 3 show the most suitable dispersion/powder for the purpose. It is an explanatory view showing one of the crushing devices. Figure 3 shows the rotor/stator assembly shown in Figure 2. FIG. Referring to these g-planes, the device 30 has the stator 3 The rotor 31 rotates at high speed inside the rotor 2. This rotor and stator Each consists of a cylinder with an open bottom. As is clear from Figure 2 In addition, a further parallel bar 33 arranged in the axial direction is provided in the lower cylinder part of the stator 32. These are separated by a single layer of slots 34 extending through the cylinder wall. separated. As seen in the bottom drawing of Figure 3, the first rotor is installed inside the stator. a plurality of slotted cylinders separated by the same number of slots 36. axially arranged parallel bars 35 separated by the same number of slots 36. It is. The rotor rotates in the direction of arrow 37. Dimensions of this rotor and stator is dimensioned such that a small shear gap 38 is formed between the outside of the two rotors and the inside of the stator. It is the law. The explanation of the dispersion/pulverization device 30 was given regarding the rotor and stator, but the same A similar effect can also be obtained by using a pair of rotors rotating in opposite directions. but.

In the latter case, the configuration is more complex and is more advantageous than the rotor/ψ stator combination. isn't it.

This liquid nitrogen-granular material slurry is directed into the bottom interior of the rapidly rotating rotor and into the primary is rapidly swept radially through the slot between the rotor and stator. rotate Due to the fast rotation of the child, the slurry is accelerated through the slots of the rotor. rotor The optimum rotational speed for - is the speed at which a circumferential speed of about 5 to 25 meters per second can be obtained. . The particles and agglomerates in the slurry then become very large as they pass through the gap 38. When shearing force and impact force are applied, the stator bar moves in the pattern shown by the arrow 3θ. -It crashes into the surface of 33. Shear gap 38 contributes to uniform mixing of particles in the slurry provide a turbulent region. A decentralized device of the type described here is manufactured by the West German Manufactured by Janka & Kunkel GMBH Ru.

The slurry stream passes through device 30 and the resulting crushed dispersed particulate mixture is routed through line 22. The slurry is then returned to tank 11, and this operation removes the lumps and granules contained in the slurry. Coalescence can be continued until a substantially monodisperse homogeneous suspension is formed. Design as follows. Alternatively, the dispersed suspension in device 30 may be further processed in the manner described below. It can also be transported through line 23 for processing.

FIG. 4 shows another arrangement of the slurry tank 11. With this method, the There is a dispersion/pulverization device 29.

Operates similarly to device 30. This dispersion! How to operate t29.

Flow the slurry through the device in the direction of the arrow to crush the lumps and reduce the particle size at the same time. reduce Usually two rotor-stator arrangements and the rotational speed of the device 29 are selected. The powder is ground more coarsely than that obtained by the device 30 and passed through the device 30 once. Form a slurry material that passes the test.

The batch in tank 11 is reduced to a particulate suspension by either device 30 or device 29. After being converted, the entire batch is then passed from tank 11 through line 24 to an intermediate tank. Take it out during 41 or 42. The tank 41 includes a stirring device 43 and a motor 44. It is equipped. Similarly, the tank 42 is equipped with a stirring device 45 together with a motor 46. There is. Re-stirring devices in tanks 41 and 42 mix particle aggregates in the suspension into the suspension. Use gentle agitation sufficient to maintain

Line 24 in the drawing communicates with tank 42 through valve 51 for discharge. . Branch pipe 25 communicates between line 24 and tank 41 via valve 52.

In this way, the granules can be suspended from the tank 11 by appropriately operating the valve 51 or 52. The turbidity batch can be directed to tank 41 or tank 42 as required. Ru. A granular solid raw material supply device 55 is separately provided to supply a certain amount of selected raw materials to the tank 41. or 42 through the introduction device 5θ. Depending on the case, When loading physically fragile materials such as brittle tempered glass or whiskers is preferably incorporated into the granular suspension prior to working up the mixture into its final form. fragile Fragile fibers and fragile materials are exposed to the high shear and shock that occurs while passing through the dispersion device 30. It may physically deteriorate due to impact force. An intermediate tank located downstream of the dispersion device 30 Introducing frangible materials into the particulate suspension in the tank can avoid such material degradation. It will be done.

Discharge pipes 61 and 62 are provided at the bottom of intermediate tanks 41 and 42. Discharge pipe 61 The flow of material through and 62 is controlled by valves 63 and 64. Vomit Both outlet pipes 61 and 62 communicate via line 65 to stabilizer 66. Ru. This stabilizing device 66 converts a homogeneous suspension of granules in liquid nitrogen into a powder. It consists of a device that puts liquid nitrogen into a form that is easy to remove. Liquid nitrogen removal is primary There are two methods: liquid-surface separation by filtration, or liquid-surface separation by steam introduction. Due to evaporation of body nitrogen. The latter method is generally preferred, with screws that have a heat exchange function. This can be easily carried out by using a -type conveyor.

Removal of a sufficient amount of liquid nitrogen from this suspension allows for further processing and separation. A stable paste or powder with no tendency is obtained. In this way, this liquid cane suspension The uniformity of the object is maintained.

The stabilized powder is then transferred by conveyor device 67 to final finishing device 68 . place Processing equipment 68 extrudes, casts, molds or otherwise pre-processes the powder into a final product 69. Any type of molding device suitable for supplying powder, such as a molding device such as a molding device, is acceptable.

In many cases, the processes occurring in device 68 include one or more components of a composition. It includes chemical reactions between more than one species of materials. Such chemical reactions include vulcanization.

Polymerization, crosslinking, etc. are included.

Intermediate tanks 41 and 42 carry out a uniform suspension of 9 particulate dispersions via a stabilizing device 66. This is for continuously transporting the processed material to the final processing device 68. first intermediate tank , then the second intermediate tank is opened by operating valves 63 and 64 accordingly. It is used as a feed source to the filter device 66. For example, one intermediate tank 41 66, tank 42 receives a new batch from tank 11. It will be done. By carefully selecting the batch size and processing speed, tank 41 can be While continuously supplying the uniform particulate suspension to the stabilization device 66, the tank 42 is filled to prepare it as a feed source to device 66.

The dispersed particulate suspension discharged from the device 30 is transferred to the line 24 via the line 23. and transferred to either intermediate tank 41 or 42. Energy in gap 38 This is because the ghee level is 1,000 times higher than with normal stirring techniques. The lumps and granular aggregates in the slurry of the invention only need to pass through the device 30 once. Shattered. In this case, repeated passage through the device 30 may reduce the fineness of the particles. This not only increases the degree of dispersion but also accommodates the increased shear energy. There is a disadvantage that heat generation occurs.

When operating in one-through mode, it is necessary to make some changes to the operation. In this case, supplement In contrast to the auxiliary dispersion device 29 or the recirculation method described above, from the device 30 the line 2 Discharge to 3. A batch of granular material is prepared in a tank 11 and stirred by a stirring device 12. Make a slurry in liquid nitrogen. The batch is then sent from line 21 to device 30 , producing a homogeneously dispersed particulate suspension. Tanks 41 and 42 are as described above. Alternately, it is the source of feed to the stabilizer 66. Batch via dispersion device 30 After processing, tank a new batch making sure the composition is the same as all batches. During preparation in tank 11, operation of apparatus 30 is interrupted. Sura from Bfflt30 Repeat the brutal operation without directing Lee to either intermediate tank 41 or 42. .

Next, the present invention will be explained in more detail with reference to Examples.

Real-” [-Kuniichi Multiple batches are created by slurrying multiple components in a rubber formulation in liquid nitrogen. prepared. Each batch had the composition shown in the table below.

Table - ! i heavy JLYfb Natural rubber 6265 Carbon black 28.1 Sulfur 1.6 Zinc oxide 2.5 Stearic acid 0.6 Accelerator, antioxidant and other additives 4.7 Conventional scale batches were prepared by weighing the ingredients according to the above formulation.

The rubber was cut to about 2 mm on each side, and the other materials were used in the form of lump powder. liquid nitrogen After slurrying a batch in a medium, a dispersion of the type described in connection with Figures 2 and 3 The mixture was passed through a machine to form a uniform dispersion. As a result, the rubber becomes extremely fine particles. When crushed, the grains and agglomerates of other ingredients were broken down and completely dispersed. Once the distribution is complete , each batch was stabilized by evaporation of liquid nitrogen to a free-flowing powder. plural The stabilized batches were combined and mixed by spinning in a double cone mixer.

Then, the stabilized mixed powder was subjected to twin-screw laboratory extrusion using a die of 50 mm x 10 mm. The mixture was pounded using a machine (Berstorff ZE 40-A type). Skri The L/D ratio of the queue is 23. The total length was 1350 mm. For the first time, the extruder Set the feed point at approximately the midpoint of the screw between 850 and 700 mm from the base. Ta. Place the kneading block element at approximately 900mm point and vent the pressure is between 1050 and 1100mm, position the gear mixer at the 1250mm point I let it happen. The extruder was operated at 85 rpm with a feed rate of 25 lb/hr. Although the product was still powdery at the vent, it was found that the product was still in powder form near the screw tip. It was found that the mixture began to flow in the gear mixer. The melting temperature is 120℃ , the extrudates were porous and rough in appearance.

Next, the positions of the kneading block and gear mixer are reversed and both are placed at the feed point. The screw was repositioned between the vent and the vacuum vent. 54rpm and A smooth surface was obtained at 30 lb/hr. However, even when operating a vacuum vent, However, some internal pores were observed in the extruded tread. Melting temperature is approximately 112℃ there were.

In the final test run of this powder sample, this kneading block was The rubber powder was processed using only a gear mixer. 30 lbs at 35 rpm /hr, a completely smooth tread was obtained. The melting temperature was approximately 105°C. Ta.

According to this test, the rubber powder prepared according to the present invention has a minimum shear element. Extrusion at very low speeds and low temperatures with short barrel lengths allows for powder pounding. It turned out to be. All these factors i.e. low temperature, lowest share, low risk The high speed and short passage distance in the extruder minimize rubber deterioration and It is possible to manufacture products of a quality that cannot be obtained with the dung pound technology.

The above examples are for illustrative purposes and are subject to many modifications.

It should be understood that modifications may be made.

international search report Special Table Sen4-503471 (7) FIC2,4 SA　32493

Claims (12)

[Claims] 1. forming a slurry of a plurality of particulate heterogeneous materials in liquid nitrogen; Agitation force and shearing force are applied to the slurry to crush the lumps and mix randomly. retaining individual particles of the material in a homogeneous suspension; and removing liquid nitrogen from the homogeneous suspension while maintaining the homogeneity of the suspension; further stabilize the suspension; At least one of the materials contains fine granular agglomerates. A method for producing a homogeneous finely separated granular mixture from two different materials. 2. A rotor that passes the stirring force and shear force to the slurry at high speed inside the stator. A claim characterized in that it is applied by passing through a dispersing/pulverizing machine consisting of: The method described in 1. 3. The rotor and stator each have an outer surface, an inner surface, and a slot wall. It consists of an end-open cylinder whose rotor and stator dimensions are fixed to the outer surface of the rotor. The size should be such that a small shear gap is created between the inner surface of the stator and the circumferential speed. A claim characterized in that the rotational speed of the rotor is approximately 5 to 25 m/sec. The method described in Section 2. 4. the mixture contains at least one polymer and other materials of the mixture is selected from the group consisting of carbon black and salts. The method according to claim 1. 5. A method according to claim 1, characterized in that the mixture contains a ceramic. 6. Mix each of the weighed different materials and make a slurry of this mixed material in liquid nitrogen. suspending to form a slurry batch; Agitation force and shear force are applied to the slurry batch to crush the lumps and separate the material. maintaining different particles in a randomly mixed homogeneous suspension; The suspension is placed in an intermediate device that prevents settling of the particles while maintaining the homogeneity of the suspension. transferring a uniform slurry batch; drawing a slurry stream from the intermediate device and removing liquid nitrogen from the drawn slurry stream; forming a powder by; A second slurry batch having the same composition as the first slurry batch is prepared, and the second slurry batch is Agitation and shearing forces are applied to crush the agglomerates and randomly separate individual particles of the material. maintaining a mixed homogeneous suspension to prepare a second homogeneous slurry batch; The first slurry batch is digested by drawing off the slurry stream. 2 transferring the uniform slurry batch to the intermediate device; and The powder is supplied with a continuous stream of slurry to stabilize it by the removal of liquid nitrogen. Continue preparing the next slurry batch at a rate sufficient to allow formation; Batch or continuous system for combining mixtures of heterogeneous particulate materials Processing method. 7. The heavy stirring force and shearing force applied to the slurry are applied to the slurry by a rotation rotating at high speed within the stator. Generated by passing the slurry through a dispersion/pulverizer consisting of a trochanter. 7. The method according to claim 6, characterized in that: 8. The rotor and stator each have an outer surface, an inner surface, and a slot wall. It consists of a cylinder with an open end, and the dimensions of the rotor and stator are fixed to the outer surface of the rotor. The size should be such that a small shear gap is created between the inner surface of the stator and the circumferential speed Claim characterized in that the rotational speed of the rotor is approximately 5 to 25 m/sec. 7. The method described in 7. 9. The intermediate device comprises a group of intermediate tanks, each intermediate tank containing a slurry. each large enough to hold the slurry in suspension; 7. A device according to claim 6, characterized in that it comprises a device suitable for providing sufficient agitation for the method of. 10. Other materials that are susceptible to physical crushing are added to the slurry batch in the intermediate tank. 10. The method according to claim 9, characterized in that the method comprises: 11. the mixture contains at least one polymer and other materials of the mixture characterized in that the material is selected from the group consisting of carbon black and salts. 7. The method according to claim 6. 12. Evaporating liquid nitrogen from the slurry stream in a conveyor with heat exchange function. A stabilized powder is obtained by further processing the powder to produce the final molded article. 7. The method according to claim 6, characterized in that: