DD248367A1 - RECIPES FOR RUBBER PREPARATIONS USING OLD RUBBER MEL - Google Patents

Abstract

Formulations for rubber mixtures with waste rubber in particle sizes smaller than 3 mm and amounts up to 200 parts, based on 100 parts of new rubber, based on natural and / or synthetic rubbers with the usual mixing components, wherein the rubber powder in the form of a rubber flour-rubber compounds, with a Mooney value in the range of 40 to 90 MEU, the rubber flour in amounts up to 400 parts, based on 100 parts of synthetic rubber, contains, is used.

Description

Field of application of the invention

The invention relates to formulations for rubber compounds for the production of rubber articles and vehicle tires using waste rubber.

Characteristic of the known technical solutions

Large amounts of waste rubber in the form of volcanic waste and of finished products such as scrap tires and other rubber products, which have not been used or lost during use, are potentially available annually as secondary raw materials because the elastic properties of the vulcanizate networks contained in the vulcanizate have remained virtually unchanged , In addition to an energetic use of vulcanizates, such. B. tires in cement production (R. Burekhart, rubber tires, Bielefeld 56 [1980] 99-100), recovers the material economic reuse of the waste rubber substance in, for example, tires or other rubber products of increasing importance.

The expectations for the material use of waste tires by pyrolysis have not been confirmed because of the unfavorable high quotient of effort and benefits (H.Simm, et al., Rubber and Rubber, Plastics 32 [1979] 23-32). Usually, therefore, the vulcanizates or a part of the protectors of the scrap tires are brought by grinding on Teiichengrößen less than 3 mm and supplied in two ways of at least partial recovery. First, this rubber powder thus prepared is incorporated in proportions up to a maximum of about 5 parts by weight directly into the rubber compounds. However, larger amounts lead to long-term difficulties (W. Kleemann, blends for elastomers, VEB Deutscher Verlag for Grundstoffind., Leipzig 1982 and M. A. Golevlev et al., Kautschuk! Resina 1982,

The rubber dust can only be incorporated into the mixture with increasing expenditure of energy. Depending on the formulation of the mixture, with increasing quantities of rubber flour, the condition is rapidly reached where sufficient homogeneity of the mixture is difficult to achieve.

At the same time, the physical-mechanical property level and especially the dynamic properties deteriorate so drastically that such vulcanizates can only be used for inferior rubber products. In addition to the problems of homogeneity, it must be taken into account that the viscosity values of the mixture increase so much upon addition of rubber powder that their further processing becomes technologically difficult or impossible. For example, the mixture Mooney increases with only 10 parts of rubber flour to 100 parts of new rubber by about 10 units, which causes considerable problems in the further processing of the mixture or the mixture is no longer usable. The compensation of this viscosity increase by an additional plasticizer oil dosage does not lead to the desired success, because it comes as a result of the "dilution" to a sustainable property decline and target products such as tires or rubber products no longer meet the requirements .. The addition of powdered rubber in quantities described in DT 2137891 from 10 to 50 parts by weight, based on the rubber component in blends, and has no practical use for the reasons described above.

Second, the use of waste rubber by thermo-oxidative degradation of Vulkanisatnetzeses and subsequent use of this so-called "Regenerates" has some importance (European Rubber J., Croydon 162 (1980) 29-31 and NE Markrik, DD-PS 148500). However, the chemical degradation of the rubber requires a relatively high cost, which substantially increases the cost of the final product, while the disadvantage of increasing the mixture viscosity with untreated rubber powder is overcome by the regenerated atif due to its low intrinsic viscosity, but greater amounts of regrind are due to damage to the product Network only limited or not usable at the previous degradation, because these damages are obviously not corrected in the subsequent vulcanization process, so that the additional amounts of regenerate must either be kept small or inferior rubber products with low demands on the physical-mechanical and dynamic B elasticity arise.

Object of the invention

The aim of the invention is. To introduce waste rubber in the form of rubber powder in rubber mixtures, wherein the preparation and processing of the mixtures must be practicable and the time and material costs to achieve the homogeneity of the mixture is not increased.

Explanation of the essence of the invention

The object of the invention is to develop formulations for rubber mixtures with Altgummimehlzusatz, which overcome the disadvantages and difficulties of the previous recipes.

The object is achieved in that the rubber powder in particle sizes smaller than 3 mm in amounts up to 200 parts, based on 100 parts of new rubber, in the form of a previously prepared rubber flour rubber compounds having a Mooney value in the range of 40 to 90ME, the bis 400 parts of rubber powder in 100 parts of rubber, is incorporated into the actual mixture. To set the desired proportion of rubber powder in the total mixture in the interval up to 66% of natural and / or synthetic rubber is added.

The rubber flour-rubber compounds can be produced in various ways.

Conveniently, the mixing is carried out during the process of rubber production or isolation of the latex or the polymer solution. Thus, the disadvantageous increase in the Mooney value as a result of the rubber dust additive can also be easily compensated by changing the molecular weight of the polymer during the polymerization.

Another way is to swell the rubber powder before compounding with plasticizer and then to produce the compound of rubber and rubber powder by mixing with solid rubber, with the polymer solution or with the rubber latex.

However, it is also possible to add the plasticizer together with the rubber powder to the solid rubber, the polymer solution or the rubber latex.

Surprisingly, it is possible according to the invention to produce rubber compounds with up to 200 phr of waste rubber without any problems. Homogeneity difficulties are absolutely excluded by the fact that the surface of the individual rubber flour particles are coated and permeated with new rubber even before the actual mixing process. Unexpectedly, the vulcanizate properties, evidently due to the achieved degree of homogeneity and because of the complete covering of the rubber slurry with new rubber, are not degraded or only insignificantly, even with large rubber dosing dosages. It adjusts itself very quickly a property level, which comes close to that of the rubber meal, according to its origin.

It is favorable to choose a so-called oil-extended rubber for compounding with rubber powder. The commonly used extender oil is distributed in the rubber dust and in the rubber. The rubber dust swells and is thus obviously able to absorb components of the vulcanization mixture in itself.

The constant volcanic properties despite varying amounts of rubber flour make it clear that a chemical bond has developed between the old and the new network.

With hitherto amazingly simple methods, significantly higher levels of rubber dust can be added to a material economy beyond what has been practiced up to now. This practicable formulation allows recycling of waste rubber using its previous elastic properties, without any mixing, processing or quality problems. The rubber dust is no longer just a quality-reducing inactive filler, but directly part of the vulcanizate network.

The main advantage of the mixture formulation according to the invention is that in the rubber and tire industry previously unachievable rates of use for waste rubber can be realized without having to accept the dreaded inhomogeneities and regarded as insurmountable increase in viscosity in the mixture. The mixtures do not "crumble" even at high levels of rubber dust.

embodiment

In the table 5 recipes are listed, wpbei the formulations I and Il represent the comparative addition of rubber powder according to the prior art. The Elastomer Compound 50 is a compound of Buna SB 170 HF with 50% rubber powder. The Mooney value of the compound is 60ME. In all cases, rubber powder with a particle size less than 2 mm was used.

Recipe w / w. I - 6.6 Il 20 III 2.1 IV 1.9 - V 2.4 NKSMR20 - 2.5 _ 2.5 _ 6.7 _ 15.0 45 14.4 Buna SB 150H 100 8.0 - 8.0 - 1.3 30 1.1 - 1.2 BunaSB177HF - 1.5 100 1.5 70 2.6 - 2.6 - 2.4 Buna ice 132 - 3.0 - 3.0 - 23.4 20 15 24.0 Elastomercomp. 50 27.5 - 27.5 30 50 40 rubber flour - - - fatty acid softener special paraffin ZnO Soot ISAF

Recipe Weighted Tie. I 27.5 2.0 1.4 1.6 Il 27.5 2.0 1.4 1.6 III IV 45.0 1.6 1.3 1.5 V Soot HAF antifouling Sulfenamidbeschl. sulfur 181.6 195.0 23.4 1.8 1.2 1.6 169.0 26.4 1.6 1.1 1.7 total 164.1 175.2

Proportion of powdered rubber (phr) 6.6 20.0 X 17.6 Proportion of rubber flour (%) 3.6 10.3 inhomogeneous 9.1 Viscous, d. Mischg. (ME) 50 61 X 46 Miscibility satisfying X Well Assessment of the mixture homogeneously X homogeneously syringability Well X Well Surface of the molding grainy rough rough Edgeending torn X smooth Appearance d. Vulkanis. smooth X smooth Vulkanisateigensch. X Strength (MPa) 11 X 12 Strain (%) 330 340 Weiterrißwiderst. (kN / m 30 ') 14 16 Abrasion (mm ³ ) 105 ' 112

33.3 14.8 52

good homogeneous

good rough smooth smooth

13,350

18 112

homogeneously

χ There was no homogeneous mixture; the vulcanization was therefore not possible.

Claims (4)

1. Formulations for rubber mixtures with waste rubber in particle sizes smaller than 3 mm and amounts up to 200 parts, based on 100 parts of new rubber, based on natural and / or synthetic rubbers with the usual mixture components such as fillers, plasticizers, anti-aging agents and processing aids, characterized in that the gum dust is used in the form of a gum dumbbell compound, having a Mooney value in the range of 40 to 90 μM, containing gum in quantities of up to 400 parts, based on 100 parts of synthetic gum. 2. formulations according to item 1, characterized in that is preferably used as synthetic rubber for compounding with rubber flour oil-plastified butadiene-styrene rubber. 3. formulations according to item 1 and 2, characterized in that the rubber powder is swollen before or during compounding with plasticizer oil. 4. formulations according to item 1 to 3, characterized in that compounds of rubber powder and synthetic rubber, prepared both by mixing the solid components on mixing or rolling mills as well as by introducing the Gummimehles in Synthesekautschuklatices or solutions and subsequent isolation of the solids used ,