JPH0338090B2 - - Google Patents

Description

Claim 1: A solid plastic in granular or powder form and a meltable component in a continuous mixer having a plurality of disc rotors on a vertical axis rotatably supported in a vertical cylindrical housing. A method for producing flowable primics consisting of additives, in which solids and additives are continuously fed at room temperature into a continuous mixer, swirled into a homogeneous mixture, and kinematics provided by a disc rotor. plastics, characterized in that the meltable components of the additive are melted and bonded to the solid components of the mixture by means of mechanical energy to form flowable granules or powders which are continuously discharged from a continuous mixer. and an additive.

2. In order to impart kinetic energy, the swirled mixture is passed through a narrow passage gap defined between the inner wall of the housing of the continuous mixer and the disk rotor, where the meltable components of the additives are melted. A method according to claim 1, characterized in that:

3. A plurality of disc-shaped rotors 15 are provided vertically one behind the other on a vertical shaft 14 that is rotatably supported within the vertical cylindrical housing 5, and these disc-shaped rotors 15 are connected to the housing. A narrow passage gap 46 is defined with the inner wall of these disc-shaped rotors 1.
A continuous feeding device 11 is provided which opens into the housing space above the rotor 5 and continuously supplies solids and additives respectively, and a product outlet is provided in the housing space below the disc-shaped rotor 5. The solids and additives that are continuously supplied to the upper housing space are mixed in the disc-shaped rotor, and the additive components are melted in the passage gap between the disc-shaped rotor and the inner wall of the housing. Flowable homogeneous mixtures of plastics and additives, characterized in that they are combined with solid components to form flowable granules or powders which are continuously discharged from the product outlet. Continuous manufacturing equipment.

4. A patent claim characterized in that the disc-shaped rotor 15 has replaceable rings 45, by means of which the passage gap 46 between the inner wall of the housing and the disc-shaped rotor can be changed. Apparatus according to scope 3.

Description The present invention relates to a method and apparatus for the continuous production of flowable homogeneous mixtures of plastics and additives.

According to the prevailing opinion, PVC high-temperature mixtures, dry blends, are below the plasticizing range of PVC mixtures, i.e. 85 or
It must be ensured that a mixture temperature of 150°C is obtained.

For soft PVC, softeners are added from 50 to 60°C. For rigid PVC, the plastic raw material is heated until it softens or melts and coagulates with added stabilizers and optionally fillers to form a flowable powder. The technology used to date does not allow for the use of intermittently operating machines for this production step, i.e. slowly rotating heatable ribbon mixers or plow plate mixers or rapidly rotating turbine mixers with small chamber volumes. , the heating mixer was often combined with a subsequent cooling mixer to provide rapid cooling of the charge. The temperature rise is related to the charge, the specific heat of the product, and the energy introduced per unit time, and since the first two parameters are fixed, it depends on how much energy is introduced into the mixture per unit time. Development was concentrated.

In hot mixing or dry mixing, i.e. mixing and simultaneous heating of PVC below the plasticizing temperature, i.e. up to about 130°C, all additives are crushed, melted and absorbed by the PVC particles. The heat-mixed product is called a dry blend. To produce the dry blend, an energy input of 100-150 kJ/Kg was deemed necessary.

Other plastic premixes are prepared in a similar manner.

An object of the present invention is to provide a method and apparatus for continuously producing a mixture that does not require a heating device.

To solve this problem, according to the method of the present invention, solids and additives are continuously fed at room temperature to a continuous mixer, swirled into a homogeneous mixture, and kinematically applied by a disc rotor. The energy causes the meltable components of the additive to melt and bind to the solid components of the mixture, forming flowable granules or powders that are continuously discharged from the continuous mixer.

To carry out this method, a plurality of disc-shaped rotors are provided vertically one behind the other on a vertical axis rotatably supported in a vertical cylindrical housing, and these disc-shaped rotors define a narrow passage gap with the inner wall of the housing, and a continuous feeding device is provided which opens into the housing space above these disc-shaped rotors and continuously supplies solids and additives, respectively. A product outlet is provided in the housing space below the child, and the solids and additives, which are continuously fed into the housing space above by a continuous feeding device, are mixed in a disc-shaped rotor and these disc-shaped rotors The components of the additive are melted in the passage gap between and the inner wall of the housing.
It is bound to the solid components, thereby forming flowable granules or powders, which are continuously discharged from the product outlet.

Thus, according to the invention, a high energy is kinetically introduced into the material, e.g. through a narrow passage gap, so that this kinetic softening causes the formation of a liquid component from the meltable component of the additive. This eliminates the need for a heating device at all. Moreover, this melting or liquefaction takes place during the mixing process, so
The liquid component can wet the solid component more uniformly.

1 shows a device not according to the invention, FIG. 2 shows the mixing device of the device in vertical section, FIG. 3 shows a plan view of the housing of the mixing device, and FIG. 4 shows a partial view of the rotor. FIG. 5 shows a top view of the rotor, and FIG. 6 shows an embodiment of the invention.

For dispersing granular or pulverulent solids with liquid components, in particular for the continuous production of flexible PVC dry blends, the apparatus shown in FIG. 1 is used.

The schematically illustrated apparatus, which is clear from FIG.
and is connected via a conduit 3 to a vertical continuous mixer 13 having a cylindrical housing 5. The length of the housing is approximately equal to twice the diameter of the housing. A container 2', which can be connected to the conduit 3, is used to contain cleaning liquid for the purification of the continuous mixer 13 when changing the liquid composition.

Conduit 3 incorporates a metering pump 6, a reheater 37 and a flow meter 7. The above-mentioned conduit 3 is connected to an annular conduit 8 surrounding the housing 5, and an injection nozzle 9 provided in the annular conduit 8 opens into the interior of the housing 5, through which the liquid component flows into the container 2. from there to the continuous mixer 13.

A weighing bunker 10 is used for accommodating the solids, at the bottom of which there is a delivery screw 1 as a continuous feeder opening into the housing 5 of the continuous mixer 13.
There is 1. The outlet of the delivery screw 11 is located slightly above the annular conduit 8 in the housing 5. Banka 1
0 and the delivery screw 11 are both mounted on the weighing platform 12. The feed screw 11 is a regulating motor _M1
Driven by.

The vertically mounted continuous mixer 13 has a shaft 14 extending downwards and provided with two rotors 15 . For driving the shaft 14 an electric motor M ₂ located above is used.

The detailed structure of the continuous mixer 13 is clear from FIGS. 2 to 5. Within the housing 5 of the continuous mixer is a bearing 28 in which the shaft 14 is cantilevered. The upper end of the shaft 14 protruding from the housing 5 has a belt pulley 29, and the drive belt 3
0 to an electric motor _M2 , not shown here. The lower end of the shaft 14 is tapered, and two rotors 15 are disposed close to each other vertically.
It has Housing 5 in the range of rotor 15
The wall 39 is smooth and above the upper rotor 15 is provided with an annular cross-section constriction 32 and one to three injection nozzles 9 for the liquid component. The entire cylindrical housing 5 is divided and can be swung open. That is, this housing is suspended on a triangular holding plate 33 and held together by tightening screws. The retaining plate 33 is on the support buffer 33', and the housing 5 is on the two supports 3
4 and one swing shaft 35. A delivery screw 11 for supplying solid primics is connected to the connection piece 36 of the housing 5.

The shape of the rotor disk 15 is clear from FIGS. 4 and 5. These rotor discs are provided with vanes 38 distributed in the circumferential direction. However, other suitable rotor shapes can be used and tangential speeds of 3 to 50 m/sec can be certified.

Due to the above-mentioned simple arrangement of the rotor and the smooth housing, the average residence of the product between the rotors or between the lowest rotor and the product outlet below is significantly reduced to preferably 2 to 5 seconds. The time gained prevents adhesion to parts of the mixer that come into contact with the product. Due to the high shaft rotation speed of preferably 2000 to 7000 revolutions per minute and the structural configuration of the mixer, approximately
It enables continuous, failure-free production of high-quality solid dispersions with minimal energy consumption of only 0.01-0.08 kWh/Kg. The axial length of the mixing zone is approximately equal to the diameter of the housing 5 of the device. The same length is required for solids feeding and dry solids disintegration, resulting in a total length of twice the diameter in the housing.

The support described above allows the shaft to be cantilevered, thereby eliminating the need for support at the outlet end of the shaft. This results in an unobstructed free outflow from the mixer, which is important during dispersion. Immediately after exiting the mixer, the product is subjected to a vacuum and degassed in the downcomer without supplying heat, which provides an economical solution.

If less liquid component is added to the mixture, so that a flowable homogeneous mixture of rigid PVC is produced, the liquid component must be generated by swirling as kinematic softening or melting from the added additive portion. No. Here uniform dispersion of all additives is more dangerous and difficult in a mixture that is easy to control.

The device according to FIG. 6 meets these requirements. The continuous mixer 13 is the same as in FIG. 1, but without the injection nozzles. PVC at 40,
Also at 43 and 44 the filler is fed separately into the housing 5 by the delivery screw 11 and reaches the continuous mixer 13. A ring 45 is tightened onto the rotor 15 to narrow the passage gap 46 between the housing wall 5 and the rotor. Since clamping rings of various thicknesses are available, the gap width can be preselected. By varying the shear gap and the rotational speed, it is possible to adapt the introduced energy to the quality requirements with unobstructed temperature stress per unit time.

Application example 1 A mixer as described above for the configuration according to FIG. 1 with a housing diameter of 100 mm is fed by a metering piston pump for the liquid components and a metering weighing belt for the solids components, and in continuous operation every mixer. At a shaft rotation speed of 7000 revolutions per minute, liquid components at a temperature of 180 °C and solids at room temperature are introduced, and 200-300 Kg/h of dispersed powder are produced continuously, immediately following if required. evacuated with vacuum. Three injection nozzles were used and two rotor discs were provided at the bottom of the shaft. The very short residence times allowed for high wetting rates and allowed unimpeded flow of the dispersed article.

2 The mixture for the flexible PVC cable compound is homogenized continuously in the same equipment as in the first example. 100 parts of suspended PVC with a K value of 65 are roughly premixed with 70 parts of ground and surface-treated calcium carbonate as a filler and 4.7 parts of tribasic lead sulfate as a stabilizer and swirled. A hot liquid component consisting of a mixture of 41 parts diisooctyl phthalate (DIOP) as a softener and 20 parts chlorine paraffin (52% Cl) as a bulking agent is injected into the chamber.

A homogeneous dry blend is obtained in continuous operation and can be stored well.

3 Example of application in the device according to FIG. 6 The continuous mixer described above with a housing diameter of 100 mm was fed with PVC, filler and additives from three weighing scales. These three solid components were mixed by vigorous swirling and passed through two narrow shear gaps with a spacing of 0.6 mm between the rotor and the housing wall. The rotation speed of the rotor is per minute
It was hot at 5000 rpm. The flowable homogeneous mixture particles thus produced exited the continuous mixer at about 95-115°C after a short average residence time. The product could be stored without the insertion of special cooling stages and without burning. Volume is 200Kg/h
Atsushi.

4. Application example As mentioned above, the following preparation makes hard hard water for bottles.
PVC plastic primitives were manufactured continuously. Clumped or suspended with a K value of 50-55
100 parts of PVC (40) are fed continuously via a weighing scale 12 to the inlet of a continuous mixer 13, and at the same time, via another weighing scale, methyl methacrylate-butadiene-styrene is added as an impact agent. Addition of 10 parts of polymer (MBS) and 1.2 parts of thio-di-octyl-stannate as a stabilizer is carried out, and via a separate weighing scale 1.5 parts of calcium stearate as a treatment agent. be done.

The efficiency of kinetic energy introduction is high with rigid PVC.
60-70%, and also soft when combined with a narrowed shear gap and simultaneously applied preheating of the softener
PVC is 45-70%.

Examples 2 and 4 are based on formulations as described in the following publications:

"BHL Compounding Handbook" by D. V. Tito et al. Publisher Buss-Hamilton Co., Ltd. 1979 CA1 page 6 and CA3 page 3 Further examples of mixtures are as follows.

(1) PVC 100 parts Softener (dioctyl phthalate) 20 parts (medium viscosity at room temperature) Stabilizer (BaZn) 3 parts (medium viscosity at room temperature) Pigment 0-15 parts (2) PVC 100 parts Softener (phthalate) Dioctyl acid) 80 parts (medium viscosity at room temperature) Filler 30 parts Additives 5 parts Pigment 15 parts (3) PVC 100 parts Polymer softener 50 parts (high viscosity at room temperature) Additives 13 parts Pigment 0-10 parts ( 4) PVC 100 parts Softener (dioctyl phthalate) 50 parts (medium viscosity at room temperature) Filler (CaCO3) 45-60 parts Additives 4 parts(5) PVC 100 parts Impact resistance agent 10 parts Filler (CaCO3) ) 10 parts Stabilizer (CaZn and Sn) 2.5 parts (paste at room temperature) Lubricant 1 part Pigment 6-8 parts (6) Polyacrylonitrile 100 parts Solvent (dimethylformamide)
200-400 parts (low viscosity at room temperature) Anti-aging agent (oxylic acid) 5-10 parts (low viscosity at room temperature)