KR910008614B1 - Direct processing of polymer with pulverrulent additives in injection moulding machine - Google Patents

Abstract

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Description

Screws and methods for processing fine grinding additives and polymers in injection molding machines

1 is a side view of a specific embodiment according to the present invention.

2 is a cross-sectional view taken along the line II-II of FIG.

3 is a partial cross-sectional view taken along line III-III of FIG.

FIG. 4 is a 1600x magnified raster electron micrograph of a sample cut from an injection molded specimen obtained from a mixture of commercially available calcium carbonate / HDPE masterbatch granules containing pure HDPE granules using a conventional injection molding screw. to be.

FIG. 5 is an optical micrograph of an injection molded specimen obtained from the same injection depth, the same material and the same method as in FIG.

FIG. 6 is a histogram obtained by an optical micrograph image analyzer shown in FIG. 5 to represent the volume fraction of filler particles or filler masses as a function of particle or mass diameter.

7 is a rest electron micrograph corresponding to FIG. 4 obtained by mixing a fine grinding additive with HDPE granules using a screw constructed according to the present invention.

FIG. 8 is an optical micrograph of FIG. 5 of injection molding obtained by mixing a fine grinding additive with HDPE granules using a screw constructed according to the present invention.

FIG. 9 illustrates what corresponds to FIG. 6 of the injection molding obtained by mixing the fine grinding additive with the HDPE granules using a screw constructed in accordance with the present invention.

* Explanation of symbols for main parts of the drawings

A: injection zone B: intermediate zone

C: discharge area 10: screw

11: drive shank 12: screw flange

13: screw core 14: screw land

15, 16, 17: Mixing device array 18: screw cylinder

20, 23: metering area 21: decompression area

22: compression area

The present invention provides a method for treating granular and / or pulverized polymer and pulverized additives in an injection molding machine as specified in claim 1 and the above treatment as specified in claim 8. It relates to a screw of the injection molding machine for.

Injection molding machines for processing thermoplastics are usually equipped with a single screw.

Injection molding machines equipped with screws serve to heat, soften, melt and homogenize the polymer material when transferring the softened polymer composition to an injection mold connected to an injection molding member capable of injecting or moving a softened or molten polymer with the screw. Heating device is installed.

For example, thermoplastic polymer granules such as polyethylene, polypropylene, polystyrene, polyamide, saturated polyester, ABS, SAN, fluoropolymer, polycarbonate, acetal resin and the like are usually starting materials.

It is an object of the present invention to provide for the direct processing of granular and / or pulverized polymers with the addition of pulverized additives exhibiting good pulverized additive dispersion.

Such additives include fillers (calcium carbonate, talc, glass beads, mica, olastonite, dolomite, kaolin, feldspar, silicates, natural and synthetic silica, gypsum), metal oxides, metal powders, pigments (titanium dioxide, inorganic and organic) Pigments, etc.), flame retardants (aluminum trihydroxide, magnesium hydroxide, magnesium carbonate, arsenic trioxide, etc.) and inorganic and organic solid products which do not dissolve in the polymer melt in the injection molding process.

Until now, such additives had to be first made into granular or master batches that could be re-suspended by expensive and complex compounding before being used in injection molding.

Internal mixer (Banbury time), twin-screw extruder with kneading element (e.g. Warner + Flyder company ZSK type or special kneader) in Stuttgart It is common to mix the additives homogeneously, such as co-kneaders located at Booth AG, Inc., located at up to 75 wt% (eg 75 wt% filler and 25 wt% carrier polymer), such as polymers or wax matrix.

The filled melt is then granulated by granulation operation.

Until now, the above-mentioned additives and thermoplastic granules could be satisfactorily processed in the injection molding machine only in the mixed form or the master batch form, so that it is possible to use a medium or high charge rate of the additive mixing which is expensive and consumes a lot of energy. Inexpensive master batch manufacturing increases the bulk price of the most important masspolymers, such as LDPE, HDPE, LLDPE, PP or polystyrene, and the most important fillers in terms of quantity, such as calcium carbonate, talt and mica.

Since injection molding always shows volume, what should be compared is the bulk price, not the weight price of the pure polymer, including the filler compound or master batch.

Thus, fillers in the above-mentioned mass polymers according to the prior art do not result in any reduction in bulk price unless they can be processed directly without prior compounding.

In the prior art, there is no known technique of directly processing the above-mentioned fine grinding additive or mixing the fine grinding additive directly. DE-PS 2,708,200 describes a static mixer, which is installed after the injection molding screw, ie between the screw tip and the injection mold, which mainly contributes to the temperature and color uniformity of the polymer melt, but they disperse solid additives. I can't let you.

DE-PS 2,838,516 describes a mixing mandrel between a screw tip and an injection mold that is fully positioned in the injection molding nozzle and uniforms the color of the melt. DE-PS 858,310 has a similar mixing mandrel. Described.

Plastverarbeiter 24 (1972) P.137 by G.Menges, W. Elbe, describes a backflow valve with a mixer function.

In known methods the auxiliary device is always used for other purposes without any deformation of the screw of the injection molding machine.

US Pat. Nos. 4,285,600 and 4,363,768 describe multichannel screws with various channel depths to improve the temperature constant of the melt and the dispersibility of the additive.

It is also known to modify materials with different melt temperatures in an injection molding machine by changing the geometrical form of the screw from DE-OS 2,840,478, ie spirals with constant screw core diameter in the kneading and mixing zones. It is described that the screw channel of is replaced by a longitudinal channel extending substantially in the axial direction of the screw and connected to each other in an annular channel.

A disadvantage of the method mentioned in the prior art is that the treatment is carried out on the principle of increasingly good rolling from the thinner layer of the polymer melt in order to lump and disperse the additives in the melt but this is economical. It is not satisfactory in terms of a suitable degree of overdispersion.

Also a disadvantage of the known method is that the modification of the known screw which is heretofore intended to be used for the above-mentioned purposes always requires the construction of an injection molding machine with a correspondingly modified screw cylinder length.

A problem with the invention is that it is necessary to adopt the method and screw mentioned at the outset which allow granular and / or finely divided polymers to be economically processed to produce high quality injection moldings.

According to the invention this problem can be solved by the features described in claims 1 and 8. Preferred features that further embody and define the invention are described in the respective dependent claims.

The staff according to the present invention, due to the relatively large mass in a particular flow, contain a mass of additives which are not dispersed in the melt and are accelerated more than the polymer matrix itself. The additive mass is broken by influences such as accelerated forces, impacts on the screw cylinder walls, impacts on the screw and mixer surfaces, impacts with other masses, and acceleration by another mixer device.

The fine grinding additive can be dispersed directly in the polymer melt without any other necessary precompounding or master batch.

This is very economically advantageous as well as low processing costs, since replacing the conventional screw with the screw according to the present invention allows direct processing in an existing injection molding machine without the cost of other large solids.

Preferably between the structure of the mixer group consisting of annular segment parts, the number of annular segments and the distance of the array of mixing elements from the injection tube piece open towards the feed zone of the screw, and between the outer diameter of the mixer and the diameter of the screw core The difference is preferably suited to the particular desired conditions such as polymer type, additive type, additive concentration, throughput, screw diameter, screw length and screw drive maximum power.

The length of the screw according to the invention is at least 19 times preferably 20 times the diameter of the screw and the minimum circumferential speed of the screw is preferably 150 mm / sec and the acceleration of the melt containing additive mass at the edge of the annular ring portion is As it occurs in the direction of rotation of the screw, the dispersion of the additive is enhanced with increasing circumferential speed. It has been found that the screw diameter should be at least 30 mm for proper dispersion.

Testing up to 40% of finely ground Calcium Carbonate (Omyalite 90T) with HDPE or PP granules is possible with a screw according to the invention with a diameter (D) of 70 mm and a length of 25 D. I knew through.

Further details, features, and advantages of the present invention will become more apparent from the following description in which the present invention is described in more detail with reference to the accompanying drawings, diagrams, micrographs, and the like, and the dispersion test method described.

1 shows a concrete implementation of a screw 10 according to the invention with a drive shank 11 immersed in a screw flange 12. Following the screw flange 12 there is a working zone with an operating length L and consisting of an injection zone (A), an intermediate zone (B) and an discharge zone (C).

The screw 10 includes a screw core 13 in which a spiral screw land 14 is integrally formed. The screw 10 also includes two mixing device arrays 15 and 16 in the injection zone A and a mixing device array 17 in the discharge zone C. The screw tip and injection mold at the end of the screw 10 opposite the drive shank are omitted to simplify the drawing as is the case with conventional drive devices for screws.

The dashed line in FIG. 1 shows the screw cylinder 18 of the injection molding machine, not shown, where the screw 10 rotates.

The diameter of the screw 10 is D and its working length L is 20D. The screw core 13 has a constant diameter E in the injection zone A up to the region near the screw flange 12 and the length of the injection zone A is 11 times the screw diameter D.

Mixer arrays 15, 16 and 17 each have a width equal to twice the diameter D of screw 10 and the distance between mixer arrays 15 and 16 corresponds to the size of screw diameter D. The mixing device array 16 is arranged at a distance corresponding to 10.5 times the screw diameter D from the left end of the screw 10 shown in FIG. 1 and the corresponding distance of the mixing device array 15 is 13.5 of the screw diameter D. It is a ship. The intermediate zone B has a length that is three times the screw diameter D.

The diameter E of the screw core 13 increases in the compression zone 19 up to the diameter F defining the metering area 20 and the diameter F is 1/3 times larger than the diameter E. The screw core 13 has a diameter G smaller than the diameter E in the depressurization region 1 at the starting point position of the discharge zone C. FIG.

The mixing apparatus array 17 is arranged in the depressurization region 21 at a predetermined distance from the intermediate region B corresponding to the screw diameter D. The distance of the mixer array 17 from the end of the screw 10, shown opposite the drive shank 11, corresponds to three times the screw diameter D.

At this interval there is a portion of the decompression zone 21, another compression zone 22 and another metering zone 23 with a diameter H larger than the diameter F of the metering zone 10.

2 shows an end through the mixer array 16. The mixing device array 16 is composed of four annular segment portions 28 formed integrally with the screw core 13. Although arranged in a total of five groups perpendicular to the longitudinal axis of the annular segment part screw and parallel to each other, it may be arranged in a spiral in another specific embodiment. The annular segment portions 25, 26, 27, 28 forming the mixing device array 16 group are arranged in the screw core 13 such that there is a constant distance I between two neighboring annular segment portions. have.

The passage area due to the gap is indicated by K in FIG.

3 shows a partial cross section through two groups of mixing device arrays 15. There is clearly shown a symmetrical profile configuration of the annular segment parts 29, 30 arranged in the longitudinal direction of the screw 10.

The profile of the annular segment portions 29, 30 has a trapezoidal shape with an acute angle of 15 °. The width of each annular segment portion 19, 30 in the screw cylinder 18 and the area of the bite is denoted by S and the value is for example 2 mm.

The distance between the annular segment portions 29, 30 is for example 10 mm. The sum of the passage areas K in the array of mixing device arrangements is greater than the cross sectional area extending vertically between two neighboring screw lands 14 and dimensioned to handle the amount of the mixture. The sum of the areas k is preferably 1.5 times larger than the area mentioned above.

This makes it possible to establish the flow state in the region of the mixer array, which makes for particularly effective dispersion. After injecting the polymer granular and fine grinding additive into the injection zone A, the melt containing the additive mass is accelerated by the edge of the annular segment part defining the passage area k laterally in the direction of screw rotation.

As the circumferential velocity of the annular segment part edge increases, additives and dispersion are of course improved. In other words, this method achieves a suitable dispersion when the screw diameter D is greater than 30 mm. The maximum number of annular segment portions per mixing device array group is governed by the properties of the strength during movement to the screw core.

For example, when the screw diameter is 30 mm and the annular segment thickness is 5 mm, the diameter of the base of the annular segment should be at least 4 mm to absorb the generated force. The height of the annular segment portion or the remaining diameter of the screw core is governed by the desired delivery action of the screw. The thickness of the annular segment depends on the force generated, for example 4-5 mm if the screw diameter D is 30 mm and 10 mm if the screw diameter D is 70 mm.

It has been found that at least 15 annular segment groups are preferably placed in three mixer arrays 15, 16, 17 on the injection molding screw 10 to achieve optimal additive dispersion depending on the screw diameter. The minimum circumferential speed of the screw is 155 mm / s.

Additive dispersion in the polymer can be checked by the following three methods.

A. Test with Leicester Electron Microscope (REM)

A 5 mm long sample was cut and cured from an injection molded product made of synthetic resin, and then ground to silicon carbide particle sizes 120, 220, 400, 600 and 1000 at 300 rpm.

It was then polished with 6 μm, 3 μm, and 1 μm diamond on a hard cloth with Strauss Blue (alcohol plus mineral oil) lubricant.

The surface was impacted with argon ions (pressure of 3 mb, current 50 mA, voltage at 1200 V for 6 minutes) and then coated with gold. REM photographs were obtained with 20keV backscattered electrons.

B. Test with an optical microscope with an image analyzer

The sample was made as in A, including polishing with diamonds.

In reflected light, filler particles (eg calcium carbonate) differed from polymer matrix (eg HDPE) in gray tones.

The image analyzer (Optomax IV Image Analyzer, G B-Leeds from Micro Measurements Inc.) and a special computer program enabled the additive mass to be directly printed out in volume percent.

C. Inspection by Extrusion Through Screen Packs

Manufacturers of pigments (e.g. titanium dioxide) or fillers have shown that dispersions of titanium dioxide in plastic in K. WOly's "Kunststoffe" obtained by extrusion through a screen pack with a defined mesh width, 70 (1980) 6.P 352).

Measure the amount of concentrate that can be extruded until the selected mass pressure is reached in front of the screen pack (accumulation of undispersed pigment masses on the screen pack) or the amount of pigment concentrate that is retained on the screen after extrusion. Decided.

The less this screen residue, the better the dispersion of the pigment or filler in the concentrate.

A screen pack of four screens with mesh width in the flow direction of the polymer melt of 400 μm, 100 μm, 25 μm and 10 μm used on the amount or on the screen or on the screen pack exchanger I-44012 Bondeno of the Palcho Company. A method of measuring the residue of the phase was used in another technique room to check the degree of dispersion that could be obtained with a new screw.

The filled part made of a conventional mixing screw, a standard injection molding screw and an injection molding screw according to the present invention is granulated and extruded through the screen pack by a laboratory extruder (Gottfert Werkstoff-Prufmaschinen GmbH, D-6967 Buchen). It was.

The test conditions were as follows.

Thread depth ratio of extruded screw: 1: 2

Extrusion Screw Speed: 75rpm

-Flat Nozzle: 2mm × 10mm

Material temperature in front of screen pack for HDPE: 200 ° C

Material temperature in front of screen fat for PP: 230 ° C

Additive amount: 1000g

First, the screen pack was weighed and installed in an experimental extruder and flushed with pure polymer molten wool. A selected amount of granulated and filled injection molding, including a total of 1000 g of additive, was then extruded through the screen pack (2 hours at 600 ° C.) and baked and the filtered additive residue from the melt on the screen pack was measured.

The additive dispersion after injection molding obtained by the method known in 1-4 in the following examples using at least some of the test methods mentioned above was investigated.

Example 1

Treatment of pulverized calcium carbonate filler and HDPE granules by conventional mixed screw

Calcium carbonate filler (CaCO ₂ ) with an average particle diameter of 3.0 μm (Millicarb) from Pluss-Staufae AG, CH-4665, Ottringen, with a charge of 20 wt% HDPE, was 80 wt. The% was premixed with the hostalene GC7260 granular (manufactured by Hoechst AG, Germany) and processed in a conventional injection molding machine.

The injection molding machine was the Netstal 300ER from Nestal-Maschinenfabrik AG, based in CH-8754 Netstal.

The diameter D of the mixing screw was 45 mm and the length L was 1125 mm.

This screw consists of a single flight screw channel with a constant 2 mm channel or a thread depth of 20 D in length, an adjacent intermediate zone in the form of a so-called Madock section of 2.5 D for shearing undissolved mixture components. It has a discharge zone with a 2.5D mixing unit consisting of an inclined offset cam.

This mixing screw is described, for example, in the magazine Plastverarbeiter (23) 1972/10, P.679.

Injection molding tests were performed at a screw elongation of 200 rpm, a specific injection pressure of 162 bar and a cylinder temperature of 200 ° C. The injection moldings produced showed that commercially available mixing screws are not suitable for direct dispersion of additives such as fillers. The injection molding contained a bulk of filler with a diameter of several millimeters.

The surface of the finished part showed marked stripes. Filtering test described in "C" using a screw pack, as shown in Table 1 and 1, even under extrusion of an equivalent amount of filler, 265 g (otherwise only 26.5% of the 1000 g of filler used in the test). This interruption led to a high pressure increase (210 bar) on the front of the screen pack.

The residue on the screen pick after baking was 867 mg.

Example 2

HDPE Masterbatch and CaCO ₂ Treatment by Standard Injection Molding Machine

Fillers such as calcium carbonate or talc and pigments (TiO ₂ , carbon black) according to the prior art are first dispersed by compounding or master batching methods in the polymers or waxes so as to be made of thermoplastics other than PVC by injection molding. Granulated. (It will be demonstrated below that similar fillers or additive dispersions are possible with the screw according to the invention without the above master batch or compound preparation).

The prior art is illustrated by Multibase SA in F-38380, a commercially available master consisting of 70 wt% calcium carbonate and 30 wt% HDPE with an average particle diameter of 3.0 μm (Millicarb) from Saint-Laurent-du-Pont. Batch granular multibase HDPE-707A was used.

The melt index of HDPE was 7 (190 ° C., 2 kg).

Prior to injection into the hopper of the injection molding machine, the master batch was mixed with a pure HDPE hostalene GC 7260 granule from Hoechst AG to a calcium carbonate concentration of 20 wt%. Selected molding machine conditions are described in Example 1.

As a screw, a standard screw for processing a polyolefin having a diameter of 70 mm and a L / D of 25, which was purchased from Netstal-Maschinenfabrik was used.

4 is a REM photograph of a specimen cut from an injection molded specimen magnified 1600 times. The method described in A was used. A clear lump was visible in the filler masterbatch.

FIG. 5 shows the photograph described in B taken with an optical microscope from the injection molding depth as in FIG. 4.

FIG. 6 shows the histogram of FIG. 5 evaluated by an image analyzer over an area of 10000 μm ² , ie the volume fraction of filler particles or chunks, as a function of the diameter of the filler particles or chunks.

The coarsest particles had a diameter of 10 μm. In the filtering test described in C through the screen pack, the injection molded parts according to Tables 1 and 2 produced the largest screen residue after baking 147 mg from 1000 g Millicarb extruded through the screen pack.

Example 3

Treatment of PP compounds and talc by standard injection molding screws

A commercially available compound hosttalene PPN 7100 TV 40 was selected, including talc with a 40 wt% fill degree from Dech-Frankfurt-Hoechst from Hoechst AG, and the molding machine and the screw were the same as in Example 2 and injection molding conditions were also Same as in 2.

Example 3 in Table 1 shows a filtering test with baked residue and injection molded specimens.

Example 4

Distance between PE granules and TiO ₂ masterbatch by standard injection screw

As a typical representative of the pigment masterbatch, Novacarome. Remafin AEX 77, selected from I-22050 Lomagna, 63 wt% TiO ₂ and 37 wt% polyethylene matrix, was selected. Filtering tests through screen packs (without pre-injection molding) showed very good pigment dispersion with baked residue on only 45 mg screen packs according to Tables 1 and 4.

TABLE 1

In Examples 5-15 below using Test Methods A-C described above, the method according to the invention and the obtained additive dispersion of the screw in the polymer after injection molding were investigated.

Example 5

Treatment of HDPE Granules and CaCO ₃ Fillers

The system described in Example 1 (20% Millicarb / 80% HDPE) was chosen and the only difference was the mixing screw according to the invention instead of the quasi mixing screw and the injection molding conditions were chosen as in Example 1.

Filler powder and polymer granules were metered directly into the hopper of the injection molding machine.

FIG. 7 shows a REM photograph of a specimen cut from an injection molded specimen at 1000 times magnification. The method used the method described in A.

Compared with FIG. 4, the additive dispersion obtained with the mixing screw of the present patent application with a slit mixer in the form of a disc shows that it is at least as good as the dispersion obtained by the above mentioned master batch treatment (Example 2).

8 shows the micrographs described in Method B under the same injection molding depth.

Compared to FIG. 5 (injection molding of the same filler in master batch form), injection of finely ground filler directly onto HDPE granules shows a relatively good dispersion effect of the mixing screw.

FIG. 9 shows a histogram corresponding to FIG. 8 of the volume fraction of the filler granules in injection molding.

Comparing FIGS. 9 and 6 shows that the method using the mixing screw has a diameter of 6 μm of the coarsest mass and a diameter of 10 μm by the master batch method.

Table 2, Test No. 5 shows that screen pack methods were found, as well as additive dispersions of quality comparable to master batches prepared by the prior art (test no. 2).

Example 6

HDPE Granular High CaCO ₃ Filler Treatment

In this example with the same conditions as in Example 5, the millicarb filler was increased to 30 wt% and the HDPE granules were set to 70 wt%.

Test number 6 in Table 2 shows that even when the filling degree is increased by 50% (from 20 wt% to 30 wt%), no significant bulk of filler is produced.

Example 7

HDPE Granulation and CaCO ₃ Filler Treatment

In the seventh test, fine calcium carbonate (average particle size: 1.5 mu m) of Omyalite 90T from Pluss-Staufer AG, which was surface treated with stearin, was selected, and the rest was the same as in Example 6.

Experience gained from filler-added polymer technology shows that good dispersion is obtained by surface coating of fillers, especially in nonpolar polymers such as polyolefins.

This is also evident from Table 2 Test 7, in which improved dispersion (more crumb residue) with finely surface-coated CaCO ₃ is obtained.

Example 8

Treatment of Polypropylene Granular and Calcium Carbonate Fillers

As the mixing screw, a mixing screw having a diameter of D of 70 mm and an L / D ratio of 25 and operating under the molding machine conditions described in Example 1 was used.

The millicarb filler was 20 wt% and polypropylene was used with 80 wt% of Propathene GYM 45 with 14-15 melt index (230 ° C./2 kg) from ICI, GB-Welwyn Ganrden.

This is homopolypropylene granular. Only 95 mg of baked residue shows good dispersion of fillers in Test 8 of Table 2.

Example 9

Treatment of Polypropylene Granular and Calcium Carbonate Fillers

Under the conditions described in Example 8, the packing of millicarb was increased to 30 wt%. The dispersion measured through the screen residue in Test 9 was somewhat worse than that of the low packing, but the quality of the surface of the finished part was still good.

Example 10

Treatment of polystyrene and fillers of ABS and calcium carbonate

30 wt% of Millicab was directly dispersed in 70 wt% of Hoist N Hostyrene N 2000 with the same mixing screw as in Example 8.

The baked residue according to test 10 shows that redispersion of calcium carbonate in polystyrene is at least as good as in HDPE.

Example 11

Treatment of polystyrene and ABS with calcium carbonate filler

20 wt% Omyalite 90T was dispersed in 80 wt% ABS granules (Lustran, Monsanto, I-Milan) as in Example 10 with a direct mixing screw 10.

In this polymer also good dispersion was obtained, as indicated by the baked residue.

Example 12

Treatment of Polypropylene Granular and Talc Fillers

Instead of the calcium carbonate described in Example 8, in this case a pulverized talc OOS type with an average statistical particle diameter of 10 mm, manufactured by Talc de Luzenac from F 9250 Luzenacsur Ariege, was used in the same manner as in Example 8. Test 12 shows a good dispersion similar to that in test 3, depending on the state of the art (precompounding with talc and PP).

Example 13

Treatment of Polypropylene Granules and Talc Fillers

The talc packing was increased to 40 wt% under the same conditions as in Example 12.

This also obtained good filler dispersion (filtering test 13) with a mixing screw.

Example 14

Treatment of Polyolefins and Color Pigments

In this case 5 wt% TiO ₂ (Tiona 472 from SMC Chemicals, GB-Grimsby) was dispersed directly on 95 wt% HDPE hostalene GC 7260 granules under the conditions given in Example 5.

This pigment concentration roughly corresponds to the maximum amount of pigment used for polyolefins in injection molding.

The baked residue according to test 14 showed good additive dispersion when fertilizing with the baked residue of the prior art (TiO ₂ masterbatch), namely test 4.

Example 15

Treatment of Polyolefin Granules and Flame Retardants

As a typical flame retardant, Martinal OL 104, an aluminum trihydroxide (Al (OH) ₃ ) from Matrinswerk GmbH, D-5010 Bergheim, was used. It was mixed directly into 70 wt% HDPE according to Example 6 and injection molding was carried out at a screw cylinder temperature of 200 ° C. (Al (OH) ₃ decomposed above 200 ° C.).

The baked residue from test 13 also showed good dispersion for typical flame retardants.

TABLE 2

Claims (20)

Injection zones, compression zones and metering zones and mixing device arrays with a constant screw core diameter, with polymer and grinding additives injected directly into the screw injection zone without pretreatment and in which the polymer is completely mixed with the grinding mill more than once Method for processing a fine grinding additive and polymer in an injection molding machine, characterized in that consisting of an intermediate section with. 2. A method according to claim 1, wherein the mixture after metering is first relaxed in the discharge zone and again mixed thoroughly before further compression in the reduced pressure zone. 3. A method according to claim 2, wherein the working length of the screw for treatment is at least 19 times the diameter of the screw. The method of claim 1 wherein complete mixing at the injection zone of the screw occurs over a length corresponding to twice the screw diameter. The method of claim 1 wherein the mixture between each mixing process in the injection zone is transferred to the screw over a distance corresponding to the screw diameter. 3. The method of claim 2, wherein the mixture in the reduced pressure region is mixed thoroughly over a length that is twice the diameter of the screw. 3. A method according to claim 2, wherein full mixing occurs before the end of the discharge zone over a distance equal to three times the screw diameter. Injection consists of an injection zone (A) with a constant screw core diameter (E), an intermediate zone (B) containing a compression zone and a metering zone and an discharge zone (C) comprising one or more mixing device arrays (17) A screw of an injection molding machine for the treatment of a pulverizing additive and polymer, characterized in that the screw (10) in zone (A) comprises at least two mixing device arrays (15, 16). The screw according to claim 8, wherein the frequent length (L) for the treatment is at least 19 times the screw diameter (D). 10. The injection zone (C) according to claim 9, wherein the injection zone (A) extends over 11 times the screw diameter (D) and the intermediate zone (B) extends over three times the screw diameter (D) and the discharge zone (C). Screw is extended over a length of six times the screw diameter (D). The screw core diameter of the injection zone (A) according to claim 10, wherein the screw diameter (D) of the starting point of the discharge zone (C) is first determined from the large diameter (F) in the metering area (20) of the intermediate zone (B). Screw core diameter G which is suddenly reduced to less than E) and extends over the area comprising the mixing device array 17 and whose length corresponds to four times the screw diameter D and then the reduced screw core diameter G And a second metering region (23) having a screw core diameter (H) larger than the metering region (20) of the intermediate zone (B). 9. The summation of the passage area as recited in claim 8, wherein each mixing device array (15) (16) (17) consists of annular segment portions spaced apart by a distance and is seen in an area between two neighboring annular segment portions. A screw, characterized in that it is greater than or equal to the cross-sectional area seen in the longitudinal region between these two screw studs. 13. The screw of claim 12 wherein the annular segment portion has a symmetrical profile. 13. The annular segment portion according to claim 12, wherein the lateral spacing of the annular segment portions disposed perpendicular to the longitudinal axis of the screw 10 in the state where the annular segment portions are parallel and disposed adjacent to each other in the longitudinal axis direction is The screw, characterized in that corresponds to the thickness of the segment part. 13. The screw of claim 12 wherein the annular segment portions are helically disposed in the screw in parallel and the lateral spacing of neighboring annular segment portions corresponds to the thickness of the ring segment portion. 9. Screw according to claim 8, characterized in that the mixing device array (15) (16) in the injection zone (A) extends over a length corresponding to twice the screw diameter (D). 9. Screw according to claim 8, characterized in that the mixing device arrays (15) in the injection zone (A) are separated by a distance corresponding to the screw diameter (D). The distance of the mixing apparatus array 17, which lies in the injection direction of the screw 10 before the intermediate zone B, from the compression zone of the intermediate zone B, corresponds to 1.5 times the screw diameter D. Screw characterized in that. 9. Screw according to claim 8, characterized in that the mixing device array (17) arranged in the discharge zone from the discharge zone end corresponds to three times the screw diameter (D). The screw according to claim 8, wherein the mixing device array (17) formed in the discharge zone (C) extends over a length corresponding to twice the screw diameter (D).

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