DE2619605A1 - Flowable mixts. prodn. - from particulate rubber, solid and liq. additives, by short term intensive mixing at elevated temp. in two stages - Google Patents

Abstract

Process comprises (i) mixing the particular rubber at 20-120 degrees C in turbulent conditions with the solid additives for 0.5-2 min. durng which time powdering takes place; (ii) introducing the liq. additives in 0.1-3 min. into the turbulent mixt. of rubber and solid additives and (iii) mixing the components under turbulent conditions for a further max. period of 2 min. The mixt. may be heated or cooled from the outside. Enables fluid i.e. flowable, homogeneous mixts. of rubbers and analogous elastomers with solid and liq. additives, to be made on a large scale in powder or granular form, suitable for further processing, using relatively simple equipment.

Description

Method and device for producing a free-flowing

Mixture of rubbers and solid and liquid aggregates The invention relates to the production of a pourable, suitable for further processing, homogeneous mixture of a rubber in powder or granular form, optionally a thermoplastic in powder or granular form and solid and liquid aggregates. The invention also relates to a device for carrying out the method.

Processes for the production of powder mixtures are known; it but has not yet been successful in producing free-flowing, storage-stable rubber mixtures technically easy to manufacture on a large scale.

The invention relates to a method for producing a free-flowing one Mixture of rubbers and solid and liquid aggregates, which is characterized is to first use particulate rubber at temperatures from 20 to 12,000 swirled with the solid aggregates for 0.5 to 2 minutes while crushing (whereby the aggregates attach to the surface of the rubber particles), then add the liquid aggregates in a period of 0.1 to 3 minutes brings in the whirling mixture of rubber and solid aggregates (where comminution is largely prevented) and then for up to 2 minutes further swirled.

Particulate rubbers for the purposes of the invention are elastomers, those with particle diameters of 1 micron to 10 0 mm, preferably 0.1 to 6 mm and in particular 0.5 to 2.5 mm are present.

Natural rubber and synthetic rubbers such as polybutadiene are particularly suitable, Polyisoprene, butadiene / styrene copolymers, butadiene / alkyl acrylate copolymers, butadiene / acrylonitrile copolymers (Nitrile rubber), polychloroprene and ethylene-propylene-diene rubbers (EPDM rubbers; the diene is generally not conjugated).

Also suitable (and included in the term rubber) are Mixtures of elastomers and thermoplastics with predominantly cold protection characteristics (especially vulcanizable blends of this type), e.g. blends of polyvinyl chloride and butadiene / acrylonitrile copolymers.

Solid aggregates are all solids that are commonly found in rubbers can be added for processing. (The amounts given below are parts by weight per 100 parts by weight of rubber). Examples are carbon blacks (2 - 200), light colored fillers such as chalk, silicates (5 - 2000), vulcanizing agents and vulcanizing auxiliaries (sulfur, Zinc oxide, accelerators), anti-aging agents, anti-ozone agents, resins, processing aids.

Liquid additives are, in particular, plasticizer oils and extender oils (5 - 170) and resins (5 - 20), e.g. phenolic resins, which are mostly used dissolved in oil will.

The first stage of the process can be carried out at 20-120 ° C. However, temperatures of about 30 to 40 ° C. are preferred.

This also applies to the second stage. In the last step you turn preferably temperatures of 30-50 ° C. Swirling means that the (solid) Substances are mixed dry, keeping them in motion mechanically, so that they stir up.

The mixtures obtained are free-flowing and storable powders with particle sizes from 1 micron to 10 mm, preferably 0.1 to 6 mm, in particular but 0.5 to 2.5 mm. They usually contain everything for rubber processing required components, so they can be processed immediately.

The liquid aggregates can be added within 0.1 to 3 minutes added continuously or with one or more interruptions. The ongoing We recommend adding small amounts; the interrupted addition in the case of large quantities.

It is important that the liquid aggregates are in the circulating material stream injected.

The device according to the invention for performing the method is characterized in that in a lockable, cylindrical container with A rotatably mounted oven clearer is provided in the center of the predominantly arched floor is, on whose drive shaft extended upwards at least one fly cutter and an overlying gyroscope with a distance are arranged and that on Container lid an adjustable, immersed into the cylindrical container Baffle is attached.

Caking on the inside wall of the container and on the mixing tool is avoided, if the product is at the specified temperature during mixing and grinding is held. You can do this by influencing the speed of the mixing tool reach.

This is also important for sticking to the inner wall of the container Temperature of the outer boundary layer of the product, so that heating or cooling of the Outer walls of the vessel can be beneficial.

They show: FIG. 1: Particulate rubber (starting material), enlarged Figure 2: Rubber + solid aggregate (enlarged) figure 3: rubber + solid aggregate + liquid! fabric (enlarged) Figure 4: embodiment the device for carrying out the method according to the invention, Figures 5 and 5: Embodiment of the device with indicated material flow.

FIG. 1 shows that the rubber particles 1 are still relatively large and no aggregate has yet been deposited on its surface.

Figure 2 shows that the rubber particles 1 by the during mixing Any internal and external forces that arise have been crushed and on their surface solid aggregates are deposited.

FIG. 3 shows that the rubber particles 1 largely retain their size but are more rounded in shape and the deposits have become larger are.

The device for carrying out the method according to the invention, as shown in Figure 4, consists of a cylindrical container 2 with lid 3. The bottom 3 of the container 2 has a curved shape. In the container 2, a bottom scraper 4 is provided in the center, which is attached to a rotatably mounted drive shaft 5 is attached. On the drive shaft continued up above the bottom scraper 4 5 at least one fly knife 5 is arranged, which comminutes the rubber particles and the solid aggregates causes. Above the fly knife 6 is on the the same shaft 5 a rotary suction knife 7 attached. The gyroscope 7 is a inwardly inclined ring, which is connected to the drive shaft by webs. The rotary suction knife 7 guides the filling material whirling in the container inwards and inwards at the same time sucks in air so that it ensures the vertical movement of the product. The fly knife 7 and the floor scraper force a horizontal movement at the same time.

Overall, the particles of the filling material move up Screw stripping through the container. The Wegforn of the particles is also determined by that on the container lid 3 fixed baffle S affects the angle of attack and immersion depth adjustable is. An electric motor 9, the speed of which can be regulated, is used as the drive. Power transmission Element are V-belts 10.

An outlet nozzle 11 is attached to the bottom of the container 2, via which with pneumatic assistance 12 the finished batch from the container 2 is removed.

Example: General regulation: A device is used in accordance with FIG. 4 with a volume of 100 1. 10 kg of the particulate Given the rubber and the solid aggregates. After closing the lid the bottom clearer / knife combination rotated and set as quickly as possible to 1500 UlMin. brought.

After two minutes, within 0.1 to 1 minute (depending on the amount) the liquid additives are added and after a further two minutes the finished product Mixture withdrawn.

Experiment 1: Mixture for the production of rubber profiles: Rubber: Butadiene / acrylonitrile copolymer particle diameter 5mm 10 kg Solid aggregates: Carbon black (Sterling 142) 6 kg anti-aging agent 0.2 kg ZnO 0.5 kg accelerator 0.15 kg sulfur 0.24 kg Ca0 1 kg liquid additives: oil (Plastikator 88) 3 kg resin (Koresin) 0.3 kg A rubber mixture with an average particle size is obtained of approx. 2.0 mm. The mixture is free-flowing (bulk density 0.5 g / cm3) and has a long shelf life. Mixing temperature 37 ° r; Mixer jacket temperature 50 ° C.

Experiment 2: Mixture for aging-resistant profiles, rubber: polychloroprene Particle size 8 mm 10 kg Solid aggregates: Carbon black (Sterling 50-1) 4- kg MgO 0.4 kg ozone protection agent 0.4 kg ZnO 0.5 kg accelerator 0.6 kg stearic acid 0.1 kg liquids Additives: oils (rubol, plasticizers) 2.5 kg The mixture has an average particle size of 2.5 mm; it is free-flowing (bulk density 0.51 g / cm³) and has a long shelf life.

Mixture temperature 450 C; Jacket temperature 500 c.

Experiment 3: Mixture for soft rubber pressure rollers: Mixture made of PVC (70 parts by weight) and butadiene / acrylonitrile copolymer (30 parts by weight) Particle size 5 mm 10 kg Solid additives: ZnO 0.5 kg stearic acid 0.1 kg TiO2 0.5 kg silica filler 1.5 kg sulfur paint 0.24 kg accelerator 0.18 kg Liquid additives: Oils 20.5 kg The mixture has an average particle size of 2.8 mm, it is free-flowing (bulk density 0.55 g / cm3), stable in storage; Mixing temperature 430; Jacket temperature 600C.

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Claims (4)

Claims: experienced in the production of a free-flowing mixture made of rubbers and solid and liquid aggregates, characterized da.'3 you first use particulate rubber) at temperatures of 20 to 120 ° C swirled the solid aggregate for 0.5 to 2 minutes while crushing, then add the liquid aggregates to the in a period of 0.1 to 3 minutes whirling mixture of rubber and solid 7.U-impact materials brings in and then swirled for up to 2 minutes. 2. The method according to claim 1, characterized in that a during mixing cools or heats from the outside. 3. Provision for carrying out the method according to the claims 1 and 2, characterized in that in a lockable, cylindrical container (2) with a curved bottom (3) a rotatably mounted bottom scraper (4) is provided in the center is, on whose drive shaft (5), which is still extended at the top, at least one fly knife (6) and a centrifugal suction knife (7) above it at a distance are arranged and a guide plate (8) adjustably attached to the container lid (3) into the container immersed. 4. Apparatus according to claim 3, characterized in that the guide plate, The angle of attack and the immersion depth are adjustable.