DE2424249A1 - PROCESS FOR THE PRODUCTION OF POWDERED RUBBER-FILLER BATCHES - Google Patents

Description

Bayer Aktiengesellschaft 2424249

Central Patents Department. Trademarks and licenses

G / Br 509 Leverkusen. Bayerwerk

y 7th MM W

Process for the production of powdery! Rubber filler

fabric batches

It is known that pourable, powdery rubber-filler batches are obtained by precipitating rubbers from the latex phase with the addition of fillers (cf. DT-OS 2,135,266; DT-OS 2,214,121; US-PS 3,714,087) However, rubber-filler batches have relatively low bulk densities (0.15-0.3 g / cm ³ ).

The object of the invention is to provide a method which allows a pre-ground rubber powder that contains only a small amount of filler as a grinding aid and therefore still tends to cake, simply with the desired amount and type of filler in a permanently free-flowing, convert powdery rubber filler batch. The fillers used as a grinding aid can Silicas, siliceous ingredients, chalk, talc, metal stearates or metal oxides.

The invention accordingly relates to a method of production a powdery rubber-filler batch, which is characterized in that a comminuted, still tending to caking rubber in a rapid mixing process filled with fillers and converted into a free-flowing powder.

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Any rubber, which has previously been subjected to a grinding process, with small amounts of the abovementioned fillers (e.g. 2 - 3 parts by weight per 10 parts by weight of rubber) can be added as a grinding aid, immediately after the grinding process together with larger amounts of filler mixed in a stirring unit (e.g. at a speed of 1000 rpm for 1 minute)

The fillers used are carbon blacks or silicas, ingredients containing silicic acid, chalk, talc, metal stearates and metal oxides in question.

Suitable carbon blacks are listed in Table 1; in the exemplary embodiment, carbon black N-770 (according to ASTM D 75-68) used

ASTM nomenclature - Ty £ N-110 SAF N-195 SCF N-219 ISAF-LS Table 1 N-220 ISAF-HM Types of soot N-231 ISAF-LM Classification of the types of soot (according to ASTM-D 1765-68) N-242 ISAF-HS N-293 CF N-294 SCF N-296 CF S-300 EPC S-301 MPC S-315 HAF-LS SC N-326 HAF-LS N-327 HAF-LS Le A 15 761

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N-330 HAF

N-347 HAF-HS

N-358 SPF

N-440 FF

N-472 - XCF

N-539 · FEF-LS

N-550 FEF

N-568 FEF-HS N-601 * 'HMF

N-660 GPF

N-683 APF

N-761 SRF-LM

N-762 SRF-LM NS

N-770 SRF-HM

N-774 SRF-HM NS

N-785 MPF

N-880 FT

N-907 MT-NS

N-990 MT

During the ruling process, the filler is absorbed by the rubber powder, which is still prone to caking and obtained from the mill, and the result is a flawless, free-flowing rubber-filler batch (bulk density 0.4-0.5 g / cm ³ ).

The stirring tools used to mix the rubber-filler combinations should have a speed of - 5000 rpm, preferably 1000 rpm. The stirred tank should be equipped with a double jacket so that there is a possibility of cooling; the wall temperature should be 20 ^° C. The material to be processed to a temperature of 20 - obtained 80 ⁰ C, preferably 50 ⁰ C while stirring process.

The volume of the stirred tank used can be between

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10 and 2000 are 1. The power consumption should be between 7 and 200 amps, but preferably 60 amps. In the present case, an 80 1 stirred tank was used, with the stirring tools were driven by a 45 KW motor.

The filling was 70 %. The agitator tools used can be designed both as a cleat shovel and as a double-deck variant tool (FIG. 1) as well as a rotary suction knife with a bottom clearer (FIG. 2). Such tools are commercially available. The stirring process can be completed in a time of 1-5 minutes, but preferably in 1 minute at the given speed of 1000 rpm. The stirred tanks can be arranged both vertically and horizontally, the horizontal arrangement also allowing the stirring process to be carried out continuously.

An advantage of the process mentioned can therefore be that rubber powder which tends to cake and which cannot be kept free-flowing over a long period of time, due, for example, to excessive cold flow (4-20 mg / min, measurement method see below), by a simple, dem The stirring process downstream of the milling process can be converted into a pourable rubber-filler batch, although the pourability achieved, measured according to ASTM-D 1937-62 (pack strength) of 30 lbs, can be described as very good. The agitator can be separated from the grinding system in such a way that light-colored and soot-containing rubber-filler batches can be produced in a simple manner without the grinding system itself having to be soiled or cleaned for the respective changeover .

In the method of the invention, therefore, they are still to be glued together rubber particles with a tendency, preferably with a diameter of 500 - 2000 / U free-flowing rubber powder produced, where a filler (carbon blacks or light-colored fillers of the

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named type) in mixing units at speeds of 200 5000 rpm, preferably at 1000 rpm, mixed in for 1-2 minutes and the energy consumption is between 7 and 200 amperes.

The filler (5 - 100 phr) pulls so quickly onto the somewhat sticky rubber particles that within a very short time Time (1 minute) a perfectly free-flowing rubber-filler batch is obtained. The particle size of the rubber filler -Batches corresponds to the particle size of the rubber particles used.

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Embodiment;

Polybutadiene is ground with the addition of 3 phr silica. The powder, which has a strong tendency to stick, was in one
High-speed mixer at 1000 rpm mixed with 10 phr SRF carbon black (N-770). After 1 minute, the free-flowing product could be drawn off. The particle size is 1.2 mm; Bulk density measured according to DIN 53 468 at 0.5 g / cm.

Natural rubber, styrene-butadiene copolymer, Ethylene-propylene terpolymer etc. transformed into corresponding free-flowing batches.

The process can also be used for all other types of rubber not mentioned here.

Measurement method cold flow:

The cylinder of the device is filled with 1.5 g of polymer; the outlet nozzle
grooves stored.

the outlet nozzle is loaded with 1 kg weight and at 50 ° C 10 min

Then relieve the test device and any protruding polymer cut cleanly.

Now store the test device for a further 30 minutes under 1 kg load at 50 ^° C., the polymer flowing out freely.

The shoot is cut off and weighed to the nearest thousandth of a gram.

The cold flow is expressed in mg / min.

Check each polymer 6 times and state the mean value.

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Claims (5)

Patent claims : 1j process for the production of powdery rubber filler -Batches, characterized in that a comminuted, still tending to caking rubber in one High-speed mixer is mixed with fillers and converted into a free-flowing powder. 2. The method according to claim 1, characterized in that as a stirring tool of the high-speed mixer cleat blade tools, Double variant tools or rotary suction knife with bottom scraper are used at a speed of 200 - 5000 rpm, 3. The method according to claim 1, characterized in that the high-speed mixer contains a double jacket. 4. The method according to claim 1, characterized in that as fillers, chalk, talc, metal stearates, metal oxides or Carbon blacks are used. 5. The method according to claim 1, characterized in that the free-flowing powder has a particle size of 500-2000 / U. Le A 15 761 509848/0246 -f. Blank page