DE10013465C2 - Bitumen with a share of polyolefin degradation wax and its use - Google Patents

Description

The invention relates to an improved bitumen with the addition of Polyolefin degradation waxes from recycled plastics and their use in road construction.

It is already known to add thermoplastics in its bitumen Heat resistance and by adding elastomers in its Improve cold flexibility. For example, styrene-butadiene-styrene (SBS) and atactic polypropylene (APP) in the roofing membrane area Application found.

Basically, TL-PmB 89, Part 1 distinguishes the following ready-to-use polymer-modified bitumens for use in road construction:

• - Bitumen A modified with elastomer
• - Elastomer modified bitumen B
• - Thermoplastic modified bitumen C.

While the use of styrene-butadiene-styrene or styrene Butadiene-modified bitumens is becoming increasingly important Products of this type sold by almost all petroleum companies are group C thermoplastic modified bitumens as well Combinations of elastomer modified and thermoplastic modified Bitumens have so far been used only little in road construction. At the Using such combinations could have a beneficial effect elastomer-modified bitumens to the important ones in road construction  Cold properties, on the other hand improved by the addition of thermoplastic Heat resistance of modified bitumens can be used.

From DE 44 44 752 A1 it is already known that amorphous thermoplastics on the Based on polyolefins in an amount of about 7 percent by weight Road construction bitumen can be added at 180 ° C. In doing so, the Thermoplastic finely dispersed in the malting phase and is to the Particle edges swelled. According to the information provided by the Manufacturer / supplier to change the rheological properties of bitumen, which mainly results in an increase in the softening point and a decrease in penetration. The ductility remains practical unchanged. To counteract the thermo-oxidative degradation during processing To protect, the thermoplastics are usually with stabilizers equipped. Nevertheless, prolonged exposure to high temperatures and oxygen degradation to decrease molecular weight take place.

It has also been reported that the addition of more suitable Waxes to bitumen or asphalt affect their application properties can be. So it has been reported that raw montan wax as Addition to bitumen the workability and the application technology Properties of the asphalt mixtures produced from it can improve. In particular, the benefits of lowering the Processing temperatures, when increasing the stability for Reduction of ruts and the possibility of paving asphalt also indicated at lower outside temperatures. Liability is also intended of bitumen in mineral aggregates such as grit can be improved.

Bituminous compositions are described in EP-A-0 553 513 A1, which contain polyethylene waxes with molecular weights of 3,000 to 6,000. The PE waxes are used in quantities of 5 to 10% based on one Plastic additive consisting of new or recycled plastics Polyethylene or ethylene vinyl acetate copolymer used. The above Formulations are cost-intensive based on the use of raw materials. The  Oxidation stability of thermoplastics in bitumen mixtures is guaranteed as in DE 44 44 752 A1.

Furthermore, WO 99/11737 A1 uses bitumens and asphalts for the production of road surface described by the addition of by a fishing Characterize the Tropsch synthesis obtained paraffin. Instead of the term Fischer-Tropsch paraffin is also sometimes used to refer to the terms hard wax and Hard paraffins or macrocrystalline paraffins are used. Fischer-Tropsch Paraffins mainly consist of normal paraffins. More than 90% are usually n-alkanes and the rest iso-alkanes. The freezing point of the Fischer-Tropsch paraffins are around 68 to 105 ° C. The addition amounts too Bitumen is between 0.5 and 10%.

WO 99/11737 A1 also describes how the addition of Fischer-Tropsch paraffin in amounts of 2.5%, 5% and 7.5% to a bitumen of grade B 100 influences its properties. The penetration (ÖNORM C 9214) decreases from 89 to 41. At the same time, the Fraass breaking point (ÖNORM C 9213) increases from -14.5 to -10 ° C. The softening point (ÖNORM C 9212) increases from 44.5 to 101 ° C when a Fischer-Tropsch paraffin from C ₄₀ to C _{50 is} used. At the same time, as a result of the improved flow behavior, the willingness to compact the asphalt is improved by adding Fischer-Tropsch paraffin. The installation times are also extended and work can be carried out at lower outside temperatures. In addition, the addition of Fischer-Tropsch paraffin to mastic asphalt reduced the installation temperature by up to 30 ° C. Finally, it is also reported that adding 3% Fischer-Tropsch paraffin to a stone mastic asphalt reduces the rake depth at 50 ° C and 20,000 rollovers from 5.7 mm to 2.2 mm.

Tests with the bitumen qualities of the types B 45, B 65 and B 80, the 4% and 6% Fischer-Tropsch paraffin were added, respectively the same results. The plasticity range (difference between Softening point and refraction point according to Fraass) could be considerable  can be improved, the Fraass breaking point changing only slightly shifts a binder level.

The Fischer-Tropsch paraffins are products made by Coal hydrogenation and downstream complex processes can be obtained. These are high-quality, pure and highly crystalline paraffins, their molecules Have C numbers from 30 to 90. If you put the general shapes. CnH2n + 2 then the molecular weight with these paraffins is max. approximately 1,200 to 1,300 g / mol compared to those from the previous ones Publications known pure PE degradation waxes (cf. 3,000 to 6,000 mol / g) much lower.

Fischer-Tropsch paraffins are produced by means of carbon hydrogenation and primary resource consumption. The process for their manufacture is like this elaborate that the products for road construction are used only at high prices can be.

A method is known from DE 195 00 425 C1 in which degradation products of polyolefin plastics in bitumen, being a The special aim of this patent is to use hot storage stable mixtures To produce extruder technology at higher temperatures. The one in the dismantling emerging low molecular weight oil and paraffin fractions, which are too much disadvantageous quality properties in road bitumen lead to Example reduced resistance to lane formation and slow setting effect, are not removed in this procedure. Also find a dirt battery mulations, derived from the recycled plastics, and the morphology the resulting degradation products are not taken into account in the process.

DE 195 12 029 A1 describes a four-stage, costly process presented with two depolymerization stages. Aim of this two stage, at high temperature and low pressure processes performed is Waxes and base oils from waste plastics. The one according to soap 4, Lines 54 to 56 in the mixing vessel remaining gap residue should be as  Find asphalt aggregate. Such an application stands but the undefined high pollution load, the unsettled and undefined Morphology and mechanical properties of the product in asphalt. The addition of the waxes produced in this way or of the gap residue to bitumen in the sense of creating a defined product in this application not described.

DE 197 02 539 A1 presents a method with which paraffins and / or high-melting waxes from polyolefinic old plastics under Removal of metallic, inorganic and mineral Impurities are produced. This is done using a two stage Circulation process between 350 ° C and 390 ° C in the first stage and 390 ° C reached up to 430 ° C in the second stage. There follows the separation of the cracked, volatile paraffin raw materials, oils, petrol and gases through a Distillation under vacuum or at normal pressure. The remaining one Bottom fraction is returned to the cycle, or 50 to 100% deducted and a selective de-oiling. The procedure takes into account not the fact that a full or partial circulatory regime between the cracking reactor on the one hand and the melting reactor on the other hand not is possible. This is because it fails in the old plastic existing impurities in the form of very fine ink, mineral and fillers etc. to a sufficient extent from the process. In addition, fine particles are formed to a considerable extent during the cracking process Coke particles and organic breakdown products. These inorganic and organic impurities and coke particles accumulate in the Circulatory mode after a short time, accumulate on the walls and heat-conducting parts of the cracking system and thus immediately prevent the further heat transfer. The cracking process will then come soon Standstill. Furthermore, the proposed selective deoiling process involves which is used for the de-oiling of standard paraffins up to a melting point of about 65 ° C. State of the art is for cleaning and oil removal high melting, dirty waxes considerable disadvantages. It is  very expensive and also extremely prone to dirt. Also in this one A defined bituminous product is not described in the patent application.

The aim of the present invention was to use a cost-effective Manufacturing process obtained high molecular and high melting The broadest waxes made from polyolefin recycled plastics Application area for bitumen, road construction bitumen and asphalt, to make it accessible.

So there was the task of using these waxes Molecular weight, melting range, their crystallinity and Characterize the molecular weight distribution and its addition to bitumen to improve its properties for road construction. Next to a row further properties of the bituminous bitumen according to the invention manufactured asphalt, such as bending strength, Processing temperature, willingness to compact, void content, was the Tendency to form a lane is an outstanding criterion for the development of the suitable waxes as bitumen additive.

In the simultaneously filed German patent application 100 13 465.1-43 is described that the high molecular weight mentioned there Polyolefin degradation waxes used in the thermal degradation of the polyolefin fraction of Recycled plastics are obtained, also in bitumen and asphalt can be used.

The subject of the present invention is therefore a bitumen, the one Proportion from 1 to 10 percent by weight, preferably from 3 to 6 Weight percent of a polyolefin degradation wax with an average molecular weight has above 7,500, preferably above 8,500, and at thermal degradation of the polyolefin fraction of recycled plastics under Exclusion of oxygen and distillative removal of the resulting gaseous and liquid hydrocarbons from remaining residue and reducing the residual ash content to an amount below 5  Percent by weight, preferably less than 2 percent by weight. This bitumen is for the production of high quality asphalt and in Road construction very suitable.

For the invention of the bitumen according to the invention, investigations with polyolefin degradation waxes with average molecular weights of approximately 1,200, 4,500 and 8,500 were carried out. The polyolefin degradation waxes used are largely free from paraffin components consisting of gases, oils and low molecular weight paraffin waxes with carbon chains shorter than about C ₅₀ by distillation, since it could be shown that a wax with an average molecular weight of about 4,500, which contains paraffinic components with carbon chains below about C ₅₀ still contained in the lane formation test according to TPA-StB 1997 edition shows the so-called slow-setting effect, ie leads to damage to the asphalt layer. In contrast, there is no slow-setting effect if the paraffin portions with carbon chains below about C _{50 have been separated} from the polyolefin degradation wax.

To determine the improvement in properties of a bitumen of class B 65, polyolefin degradation waxes with average molar masses of about 1,200, 4,500 and 8,500 were added in quantities of 5 percent by weight and test specimens were produced therefrom. These test specimens were also subjected to a comparison with test specimens which contained other bitumen additives in a water bath at 30 ° C. with a 5 cm ² stamp and a load of 25 N and the depression in mm was determined over the load time. It was found that the degradation wax with an average molecular weight of about 8,500, which had been freed of all paraffinic components with carbon chains below about C ₅₀ , gave the best results. In addition to the higher average molecular weight, this product also had a higher crystallinity than the other polyolefin degradation waxes. The degree of crystallinity increases from an average molecular weight of 1,200 to 8,500 from 40% to 55%. The polyolefin degradation wax with an average molecular weight of 8,500 was therefore used for the further tests.

Table I shows the tests on bitumen, which with Polyolefin degradation wax made from recycled plastics has been modified:  

Table I

Table I shows that an addition of 5% of the above Polyolefin degradation wax to a B 65 to reduce the Needle penetration (DIN 52010) leads from 55 to 28 × 1/10 mm. The softening point (DIN 52011) is determined by the addition of wax raised by 10 ° C, so that in this application example a Increasing the plasticity range by 10 ° C is achieved. This The result is all the more positive than the breaking point according to Fraass, there is no negative change and the down The temperature behavior of the bitumen is completely preserved remains. Other application examples with soft bitumen types, for example a B 80, result in higher values in the lowering penetration and raising the softening point. As The result of this series of experiments shows that with the Wax additive from softer types of bitumen, for example B 100 or B 80, harder types of bitumen, for example B 65 or 45, can be produced.  

The effects of mixing time and mixing temperature are in Table II using the example of a mixture of 95% bitumen B 65 with 5% polyolefin degradation wax shown:

Table II

It shows that an increase in mixing time and mixing temperature almost no influence on the solidification point (DIN 52011). That is why the wax can already be used mix into the basic bitumen for a short time.

Another important criterion is the adhesive property of the bitumen modified on the rock with the wax. The attempts were made according to Dr. Potschka performed.

Table III shows the most important results using the example a mixture of 95% B 65 with 5% polyolefin degradation wax compiled:

Table III

While with conventional road construction bitumens the adhesion limit Viscosities for quartzite between 4 and 5 could with the addition of wax to a B 65 achieves a value of 7. Thus the addition of wax results in an improvement in Rock liability.

Table IV shows the test results on one Asphalt back extracted binder. It became their own of a Stan offset with the asphalt binder 0/16 dardbitumen B 65 compared to a bitumen, the additional 3% polyolefin degradation wax were still added.

Table IV

The results show that the positive properties, which is achieved by adding the polyolefin degradation wax such as needle penetration and softening point (ring + ball ° C) also in the extracted binder find. The Fraass breaking points also show on extracted binder with added wax even cheaper Values as on the extracted binder without wax, what the good cold properties of the wax additive again underlines.  

The properties of asphalt mixtures to which the polyolefin degradation wax according to the invention had been added were then investigated. One of the most important properties for the effect of wax additives to asphalt and bitumen was the track formation test according to TPA-StB, 1997 edition. The test plates required for the track formation test were produced with a segment compressor. Since a path-controlled compaction was chosen, the degree of compaction could be specified via the reference space density of the Marshall test and the mix weight (here 100%). The test panels were made with a thickness of 8 cm. Table V shows the results of the track formation tests on different asphalt mixes:

The results show that the depth of the ruts through the Addition of the polyolefin degradation wax according to the invention improved has been. There were average values of 1.72 mm at one Mixture of B 65 with 5% wax and an asphalt binder 0/22-DS and 2.41 mm with a wax addition of 3% with an asphalt bin the 0/16 determined. The reference value without the addition of the polyol finabbauwachses with 3% wax addition and an asphalt binder 0/16 2.86.

Table VI shows the influence of the addition of wax on the Compactibility of the mix with and without the addition of 3% Polyolefin degradation wax shown. The results show that the spatial density is increased by the addition of wax and the voids can be reduced.

Table VI

The excellent cold properties of the polyols Bituminous wax modified can be used on the transferred asphalt samples transferred. The asphalt binder 0/16 with B 65 was with and without the addition of the polyolefin degradation wax subjected to a test of the cold bending tensile strength. The Results are shown in Table VII:  

Table VII

The sample made with the addition of polyolefin degradation waxes then has a higher bending tensile strength and shows at -20 ° C only a very slight difference to that at 0 ° C value obtained. In addition to tests in rotating Pistons according to DIN 52016 were also further aging tests carried out with the model pot process. It was on Material quantities of 3 kg basalt chips 8/11 mm and 1.5 GT Binder used. The model pot consists of an electrically heated pot with external wall insulation and Perforated plate to which the mix is loosely applied. It an oxidative aging over one hour in a Air flow of 500 ml / min. performed at 140 ° C. As well a distillative aging with 500 ml / min. Nitrogen at 140 ° C carried out. Both attempts are compared with containing a B 65 binder and a B 65 binder the polyolefin degradation wax performed. The results showed that the observed increases in the softening points of Mixtures with the wax are comparable to the mixtures without added wax. Even the measurement of the resulting Ductility and breakpoints according to Fraass showed no negative Characteristics.

Claims (14)

1.Bitumen, characterized by a proportion of 1 to 10 percent by weight of a polyolefin degradation wax with an average molecular weight above 7,500, which occurs during the thermal degradation of the polyolefin fraction of recycling plastics with exclusion of oxygen and distillative removal of the resulting gaseous and liquid hydrocarbons with up to 50 carbon atoms from the remaining one Residue and reduction in residual ash content is formed to an amount of less than 5 percent by weight. 2. Bitumen according to claim 1, characterized in that the Contain polyolefin degradation wax in an amount of 3 to 6 percent by weight is. 3. Bitumen according to claims 1 and 2, characterized in that the polyolefin degradation wax has an average molecular weight of over 8,500. 4. Bitumen according to claims 1 to 3, characterized in that the residual ash content of the polyolefin degradation wax is less than 2 percent by weight lies. 5. Bitumen according to claims 1 to 4, characterized in that the X-ray crystallinity of the polyolefin degradation wax 50%, preferably over 55%. 6. Bitumen according to claims 1 to 5, characterized in that the softening point of the polyolefin degradation wax above 90 ° C, is preferably above 98 ° C.   7. Bitumen according to claims 1 to 6, characterized in that the penetration measured at 20 ° C., 100 g and 5 sec under 5 × 1/10 mm, is preferably less than 3 × 1/10 mm. 8. Bitumen according to claims 1 to 7, characterized in that it additionally styrene-butadiene polymers in amounts of 1 to 5 Percent by weight, preferably in amounts of 1 to 3 percent by weight. 9. Use of bitumen according to claims 1 to 8 for the Road construction. 10. Use of bitumen according to claims 1 to 8, characterized characterized that it was used to produce an asphalt mix Mixed aggregates such as sand, gravel or grit becomes. 11. Use of bitumen according to claims 1 to 8, characterized characterized that it is used to lower the processing temperature of Asphalt is used. 12. Use of bitumen according to claims 1 to 8, characterized characterized in that it increases the hardness and reduces the Track formation tendency of asphalt is used. 13. Use of bitumen according to claims 1 to 8, characterized characterized that it improves compressibility and Reduction of the void content of asphalt is used. 14. Use of bitumen according to claims 1 to 8 for one Road surface, characterized in that it is used to manufacture it Base layer and / or its tie layer and / or its cover layer is used.